Chapter Text

Episode I

Ignition

Prologue

A Scene of Confrontation

「対峙の風景」

(Taiji no Fūkei)

Day 21 Month 10; 02:10 Japan Standard Time

Somewhere in the Kantō Region

At the edge of the celestial sphere—in other words, the blue boundary that enclosed within it the land that could be called the embodiment of the Earth Mother herself—

There drifted a single artificial object.

A cylindrical body sprouting antennas and solar panels spread wide like wings to either side, it bathed directly in the harshly descending sunlight. It scattered a dazzling, almost painfully glaring brilliance into the surrounding blackness, the domain of the stars. Since she had come to occupy a corner of the heavens three years earlier, after launching from the earth below, this had been her relentless daily existence—a fate imposed upon her until the day her strength failed according to her predetermined lifespan and she returned once more to the warm embrace of the celestial sphere.

She was an artificial heavenly body constructed from metals and synthetic materials, things far removed from anything natural. For three years since her birth and ascent, she had continued to gaze upon a corner of the continent spreading far below her, some 900.000 meters beneath, through eyes of electronics and metal. And before she reached the end of her designed service life, more than six years still remained. During that time, everything captured by those electronic eyes—eyes akin to clairvoyance—would continue to belong to the people on the ground who watched over and controlled her operations from a secluded corner of the world.

She—her name was the imaging geodetic satellite Izuna.

Somewhere in Japan’s Kantō region stood the facility that controlled her, the satellite that had made orbit her home since her launch three years earlier. Its location and even its name would never be made public. There, controllers and intelligence analysts worked around the clock, devoting both mind and body to a silent struggle as they sought to extract the information desired by the organization to which they belonged. That covert contest, having begun in the morning and passed through the day, had now crossed into the realm of late night.

Publicly, it was called the Transference—a movement through space-time caused by a phenomenon beyond the explanatory reach of all the scientific knowledge humanity had ever accumulated. As a result, Japan had been severed from the world in which it had survived as a nation and as a people. Multiple communications relay satellites and imaging geodetic satellites had come to reside in orbit as part of the infrastructure necessary for Japan to continue existing as a state and for its people to survive. Yet at the same time, those satellites also served as ears and eyes intended to gather intelligence on a global scale, protecting Japan, now stranded in another world, from any threats lurking around it. A wide-angle information display terminal continuously collected and displayed the radio signals and imagery gathered by the satellites. After being analyzed by operators, the information was simplified and clarified before being presented. Since around midnight, the display had been tracking the entirety of the Japanese archipelago and the surrounding seas and skies, along with multiple points of light and symbols moving across them. This space specialized not only in handling satellite data but also in collecting and managing information from antennas, surveillance cameras, listening devices, and dedicated personnel secretly deployed both within and beyond Japan by the “Organization” that operated it. In other words, on this day, much of the Organization’s intelligence-gathering capability had been concentrated here, and the facility continued to stir with anticipation as it prepared to monitor whatever was about to occur around Japan.

In the depths of that facility, there sat a solitary figure, reclining in a chair, attended by several others.

“Chief Cabinet Secretary, it will begin shortly.”

“………”

The backrest of the reclining chair rose slightly in response to the call from the suited man beside it. It was the chair’s occupant’s silent reply. The room was dark compared to its vast size. Aside from the immense wide-angle display and the consoles operated by staff, there were no significant sources of light. Even the chair’s occupant, watching the screens from a distance, was swallowed by the shadows cast in contrast to the displays’ glow, making it impossible to discern his appearance. Yet that very obscurity lent the man addressed as the Chief Cabinet Secretary an air of authority befitting the ruler of the entire space.

“Transmission pattern confirmed… ‘Romeo’ appears to have begun moving.”

“Well then… let’s take a good look at it. The true capabilities of the Self-Defense Forces.”

The chair’s occupant spoke quietly, but his voice was swallowed by the atmosphere of the room as it shifted from stillness to motion in response to the changes unfolding beyond the monitors. No one around him heard a word.

Day 21 Month 10; 02:14 Japan Standard Time

Miho Signal Intelligence Station, directly under the Intelligence Headquarters, Sakaiminato City, Tottori Prefecture

Night had deepened further, swallowing the entirety of its bizarre form into the heart of darkness.

The space, composed of a total of 32 antennas, resembled a work of avant-garde art. Since its construction, it had functioned as Japan’s ears, never once surfacing into public view, and had contributed to the nation’s defense in the form of intelligence provision. A “signal intelligence station” for intercepting and collecting radio and communication waves traveling to and from outside Japan. Six such stations existed within Japan, and in this other world, it was said that the number exceeded ten if the same type of simple facilities unofficially deployed abroad were included.

Among these signal intelligence stations, Miho Station in Sakaiminato, Tottori Prefecture, was one of the six major domestic stations that could be called a mainstay. It had operated since before the Transference to probe the movements of Japan’s neighboring countries. Its communication interception targets extended not only to surrounding hypothetical enemy nations such as Russia, China, and Korea, but also to vessels and aircraft of unknown nationality traversing Japan’s territorial waters and airspace over the Sea of Japan. And up until the very moment the Transference occurred, Miho Station had devoted itself wholly to the task of listening, without any major incident.

After the Transference, just as the position of the Self-Defense Forces itself underwent a major change, the state of signal intelligence stations as intelligence-gathering facilities also faced significant transformation. As the years passed following the Transference and the fact that no major threats existed in Japan’s surrounding region became clear, calls arose for the consolidation and reduction of the SDF, a national defense organization. Similarly, signal intelligence stations, the terminals of the intelligence-gathering apparatus, were also targeted for consolidation and elimination. That these plans were never ultimately carried out was due not only to the deep-seated unease toward the unknown world surrounding Japan, but also significantly to the fact that, during the East Asian Turmoil before the Transference, a not inconsiderable understanding of national defense had taken root among Japanese citizens as taxpayers. Then, the revelation of a “threat” less than a decade after the Transference completely dispelled any discussion of disarmament.

Currently, Japan is confronting that threat.

It could never compare to the era before the Transference, when Japan faced military powers like Russia, China, and Unified Korea—nations that had repeatedly violated its surroundings overtly and covertly—with all their might. Yet, a clear hypothetical enemy nation now existed for Japan. After what was called the “Sloria Conflict” in the postwar period, the sea stretching beyond, now formally designated the Sea of Japan (“Zeno di Nihon”), separated Japan from the western half of the Sloria subcontinent. The Republic of Lorida, designated “Romeo,” had violated that land under the name of “enlightenment” with its overwhelming military force. After repeated concessions, Japan ultimately severed the path to peace with them, and three years ago, the two nations turned to military conflict on the Sloria subcontinent. The course and outcome of that struggle defied the expectations of most observers.

“A Japanese-made computer game war.”

A newspaper from Japan’s neighboring nation, the Neuterane Federation, concluded its special feature on the Sloria Conflict with that single line. Although based on unilateral disclosures from Japan’s side, the entirety of the combat was broadcast without omission on television and computer networks, evoking astonishment. Among these broadcasts, particularly striking were the scenes not of battle, but of destruction, where targets were unilaterally shattered by bombs, shells, and missiles, as if in a computer shooting game. The targets being destroyed in infrared imagery were, naturally, the tanks, bases, and warships of Lorida’s military, Japan’s adversary. This was so shocking, so beyond conventional military wisdom, to some nations that had believed in the superiority of the military power that was Lorida before the war. In the span of just over two weeks from the start of the Sloria Conflict to its ceasefire, to borrow the words of a military expert from a certain great power, “In just two weeks, the most modern armies we possess in this world were reduced to armies of the distant past.” Since then, Japan came to be regarded as a major military power in this other world, and the Republic of Lorida became its hypothetical enemy nation. However, with no diplomatic relations currently existing between the two countries, Lorida’s official handling by Japan—as evidenced by its assigned alias “Romeo”—amounted to the extremely vague government view of “an armed faction of unknown affiliation illegally occupying western Sloria through military might.”

Miho Signal Intelligence Station covered an interception area spanning from the entire Sea of Japan it faced to the far west, its reach occasionally extending to the southern tip of Lorida proper, the “armed faction” located northwest of Japan. During the Sloria Conflict, Miho Station had focused the full extent of its interception capabilities on grasping the movements of Loridan ground forces deployed on the Sloria subcontinent even before the war began, succeeding in completely tracking their actions. In other words, as long as it was limited to information warfare, this place was the very front line, and its critical standing had only grown more pronounced after the Sloria Conflict.

Thirty-two in total. The control room overseeing the communications interception antennas, referred to as an “elephant’s cage” due to their characteristic circular arrangement, was perpetually dim, and even the presence of the intelligence officers operating the interception equipment felt like just another component of the giant machine that was the signal intelligence station. Their primary “surveillance target” remained the armed faction still colonially dominating Nodocor in western Sloria. However, since the Sloria Conflict, the focus of interception in Sloria had shifted from communications between Loridan military units—the “armed faction” in Nodocor—to communications between those forces and their homeland. The agreement concluded between Japan and Lorida after the ceasefire resulted in a phased reduction of Lorida’s colonial forces over five years, now in progress. As a result, the possibility of large-scale ground combat erupting again on the Sloria subcontinent had been all but lost. This was due, more than anything, to Lorida itself still not having recovered from the material and psychological shock and damage it suffered in the Sloria Conflict. Yet, in less than two years since the conflict’s end, a change that could not be overlooked had also been born.

“Sector 18, transmitting. Power increasing… Frequency, database cross-check complete. Guidance signal.”

The report came from an intelligence officer staring intently at a control terminal. That was the moment the stillness that had ruled the space yielded its throne to commotion. A massive wide-angle terminal dominating the front of the control room, divided by vertical and horizontal axis lines, constantly displayed the entire Japanese archipelago, the full coastline of the Sloria subcontinent, and the surrounding ocean expanses. Simultaneously with the report, a single point on the topographical map flashed red. The location was over the Sea of Japan.

“Transmission source pinpointed. Latitude 41 degrees north, longitude 136 degrees east. The source is accelerating, moving southward.”

“Emergency communication to the SF (Surface Fleet) command. And an urgent message to the Coast Guard as well. Hurry…!”

“…Still, Commander, it's almost surprising they were allowed to roam free this long. What is the Defense Ministry thinking?”

The deputy commander, stationed beside him, addressed the station chief, who was positioned on the topmost tier of the terraced control room. Two men: a Colonel in the GSDF and a Captain in the MSDF. The intelligence officers working in the control sections below them also displayed a diversity of rank insignia, representing ground, maritime, and air forces. Among them were personnel on temporary assignment from the National Police Agency, the Public Security Intelligence Agency, and the Japan Coast Guard. Though under the jurisdiction of the Ministry of Defense, the signal intelligence station could be called an integrated unit of intelligence agencies from across government ministries. However, the post of station chief was a reserved seat for active-duty senior officers of the Ground, Maritime, or Air Self-Defense Forces.

“Message received from SF command. Two escort vessels on patrol, moving at maximum combat speed toward the transmission source.”

“The patrol aircraft is reaching overhead the transmission source in ten minutes!”

Gazing at the control panel that showed the pursuit of the transmission source had begun both over the radio waves and physically, the station chief, a Colonel, spoke.

“The signal sample arrived from headquarters. The one Higashi-Chitose detected first.”

“Ah… yes, it was a bomber callsign, wasn’t it…”

“Correct. That theory had been strong ever since the initial collection, but because the source was their homeland, intercepting high-precision signals was difficult due to the distance. However…”

“………?”

“Through close-range intelligence-gathering activities, it was finally confirmed just the other day that it is the same callsign.”

“I see…”

The deputy commander, a JMSDF Commander, uttered something like a groan. It had a ring of assent, as if he had already known the facts sufficient to justify his understanding. “Close-range intelligence-gathering activities,” so it was indeed… His musing had barely begun to take root when he noticed the Colonel looking up at him out of the corner of the Commander’s eye, and he endeavored to focus his mind on the situation at hand. Even now, long after calls for the joint operation of ground, maritime, and air forces in preparation for “the future war to come” had become commonplace, facts that could not be spoken of lightly between fellow SDF personnel were often present. Especially since those “intelligence-gathering activities” belonged to a higher level of defense secrecy, and the Maritime Self-Defense Force to which he belonged shouldered the greater part of that duty…

“…I’m not entirely convinced myself, but if they were just sneaking around to eavesdrop, that would still be one thing. That is the Ministry’s view. But what they are trying to do now—”

“…Indeed, this is a serious act of violation.”

The deputy commander nodded.

It had been confirmed that “Romeo” spy vessels disguised as fishing or merchant ships first began to appear in Japan’s coastal waters roughly half a year after the Sloria Conflict ended. Suspicious radio waves that began emanating intermittently from the waters off Hokkaidō, the Sea of Japan, and even from around the Ogasawara Islands straddling the Japanese mainland at around the same time served as the trigger for the Intelligence Headquarters to detect the presence of intruders who had stepped into the nation’s backyard. Subsequently, images of these vessels were captured and photographed by JMSDF patrol aircraft and Coast Guard patrol vessels deployed to the relevant sea areas based on reports from the Intelligence Headquarters, confirming with certainty the existence of these uninvited guests. Though outwardly resembling the small and medium-sized merchant ships and fishing boats widely seen in Japan’s neighboring countries, these suspicious ships possessed more than enough telltale elements—the unnatural arrangement of fishing gear, uninhabited decks, and antennas disguised as rods or masts—that an informed observer would recognize immediately for what they were.

Afterward, by analyzing their communication patterns and tracking their navigational tracks, it was even determined that they operated from ports within “Romeo” territory or areas under “Romeo’s” influence. And that they were intercepting communications within enemy nation Japan… As a signal intelligence station, its role had been simply to continue broad intelligence-gathering activities while constantly monitoring “Romeo’s” peeping actions and reporting to headquarters in Tokyo. However, that had only been the case up until the other day.

It began with a single callsign. From radio intelligence collected up to that point, the Intelligence Headquarters had determined that a base for large bombers existed at the southern tip of the Republic of Lorida proper, and from records of communications during training and patrol flights, it had come to grasp the number of bombers stationed there, the callsigns assigned to individual aircraft, and even the frequency of flight training. Then, the previous month, an aircraft with a new callsign had been deployed there. The aircraft’s unique communication patterns, clearly different from the others, drew the attention of the Intelligence Headquarters. As a result of close-range intelligence-gathering activities conducted to enhance the precision of signal intelligence collection, the information uncovered was astonishing. They had deployed an aerial refueling aircraft, modified from a bomber of the same type. Furthermore—

—That aerial refueling aircraft had, the other day, moved to their colony far to the south of their homeland. This occurred at almost the exact same time that suspicious ships, distinctly different in character from the intelligence collection vessels seen before, had appeared over the Sea of Japan.

Once again, Miho Signal Intelligence Station.

“Sector 18, communicating. Believed to be encrypted communication.”

“…Run it through clearing. How long?”

“…Five minutes until interception is possible.”

Thanks to the abundant practical experience from before the Transference, combined with advances in equipment and higher-performance computers, the Intelligence Headquarters had now completely grasped the encryption patterns used by the hypothetical enemy, the Loridan military, and by extension its government. They used a typical one-time pad cipher, and occasionally employed a cunning method called “burst” transmission, where communications were compressed and sent in short pulses, but the disparity in capabilities between the two sides was so great that even this could be dealt with in a short time. To give one example, a one-time pad requires frequent pattern changes to prevent its structure from being deduced from patterns, but the cryptanalysis division of the Defense Intelligence Headquarters (DIH) had developed dedicated analysis software to address this, rendering it a non-issue. Meanwhile, those on the intercepting side naturally needed countermeasures of their own, and in this field, when the technological capabilities of both sides were evenly matched, it was usually fated to become a cat-and-mouse game. In fact, even having a technological advantage offered no grounds for complacency. In that regard, Japan had a bitter history of defeat. Long before the Transference, at the outbreak of the Pacific War, the Japanese Navy had boasted of the impregnability of its operational ciphers, but its adversary, the US military, not only deployed a dedicated code-breaking team but even brought in a dedicated electronic computer, completely laying bare the entirety of the Japanese Navy’s ciphers in a matter of days. And, in an egregious blunder, the Japanese Navy itself only realized after its defeat that its ciphers had been completely decoded by the enemy, and that it had been outmaneuvered in every operation it had planned.

The intelligence officer’s report continued.

“Radio database cross-check complete. Callsign ‘Kizlasa.’ No mistake.”

“…Controller, where is the location of the communicating party?”

“…Approximately 700 nautical miles northwest of Hokkaidō. Higashi-Chitose Station has also confirmed, tracking the communicating party.”

“Clearing complete. The communicating party is believed to be an aircraft... Matches callsign ‘Kizlasa.’”

“————!?”

The station chief slightly lifted himself from his chair. A glistening sheen, suggesting cold sweat, seeped at his temple.

“So it is as I feared…”

What he had dreaded had come to pass. The suspicious ship over the Sea of Japan was no mere intelligence gathering vessel. It was now poised to bring a threat far greater to the Japanese mainland.

“ASDF Chitose Base, interceptors scrambled!”

An order had likely gone from Higashi-Chitose Station, through the main headquarters, to the Northern Air Defense Force. Even so… the station chief thought. It was fortunate that they had managed to grasp the force scale of the enemy’s long-range bomber fleet and their dedicated aerial refueling aircraft, and identify their callsigns, just in time…

And then…

Those who had made the greatest contribution to intelligence gathering were, even now, somewhere at sea—

Day 21 Month 10; 02:30 Lorida Domestic Standard Time

100 kilometers off the coast of Cape Laurtage, southern tip of the Daltrant Archipelago

JMSDF submarine SS-504 Kenryū

Their mission was called the “Lorida Local.”

An eternal darkness seemed to rule the world the boat traveled through. As the hours passed, that darkness grew deeper still, as if intending to swallow the vessel, over 80 meters in length, into its stomach. Whether it was the sound of the propulsion or the creaking of the hull resisting the water pressure, any noise the ship did make was far too small, vanishing as if sucked into the depths of the darkness that dominated the sea.

“…Scheduled report. The boat is submerged and navigating the target area. 20 minutes until the scheduled surfacing time. Battery status, no abnormalities.”

“Understood. Continue the mission.”

The report came from the ship’s Number One, Torpedo Officer Lieutenant Commander Yūichi Sugiyama. The captain, Commander Hiroyoshi Ninohe, commanding officer of JMSDF submarine SS-504 Kenryū, listened without taking his eyes off the nautical chart. For the past few days, the electronic chart had been displaying that the Kenryū, under Commander Ninohe’s command, was in the coastal waters of the southern tip of a certain archipelago. Given the season, the heating inside the ship, dominated by red night lighting, was starting to function. Yet to a considerable number of the crew, the lukewarm air flowing through the pipes packed tightly in every direction, combined with the enclosed space, seemed to create an unfathomable eeriness instead. The ship’s phone rang. Reflexively picking it up after a single ring, Commander Ninohe received a report from the engine room. It was Chief Engineer, Lieutenant Commander Aki.

“Captain, AIP module inspection complete. No abnormalities.”

“Understood. Good work.”

“Captain, excluding the return trip, we still have three days’ worth of AIP fuel remaining. What shall we do?”

He understood what the Chief Engineer was getting at. The AIP (Air-Independent Propulsion) system, which primarily uses onboard liquid oxygen and kerosene as fuel, could allow for submerged cruising for over two weeks without surfacing once, provided its use was limited to low-speed cruising at 6 to 7 knots. In theory, if they started from the northern limit of Japanese territorial waters and used only AIP for a week outbound, they could easily reach their destination—the “Romeo’s stronghold,” the mainland of the Republic of Lorida—while remaining submerged. But Commander Ninohe, like many submarine captains, also used low-speed cruising on battery power in addition. The AIP system was both a “magic foot” enhancing the submarine’s stealth and an insurance policy for emergencies. For a conventionally powered submarine that depended on diesel engines and the batteries they charged for propulsion, the ability to operate within enemy-controlled waters without surfacing—an act that greatly increased the risk of detection by radar or sonar—was an enormous advantage. Even with its limited power output and endurance, having acquired a means of long-duration submersion that had previously been the exclusive domain of nuclear submarines back on Earth could be called an epoch-making turning point in the history of conventionally powered submarine development.

“We’ll manage on batteries for the time being. I’ll issue new orders if we need to use AIP.”

“Understood.”

The JMSDF Sōryū-class submarines, to which the Kenryū belonged, were acclaimed as the world’s highest-performance attack submarines in this world. They were the first operational submarines to be equipped with an AIP system, and their commissioning, combined with a submarine fleet reinforcement plan promoted before the Transference, dramatically improved the operational capabilities of the JMSDF submarine fleet. It not only expanded their operational range and potential submersion time but also led to improvements in the intelligence-gathering capabilities of the Self-Defense Forces as a military organization. That importance remained unchanged after the Transference, and had even grown. Of course, the very idea of deploying conventionally powered submarines without any hesitation in the open ocean far from home, on long-term operations exceeding a month, was considered utter lunacy by the few other countries in this world capable of operating submarines, including that “Romeo”…

…The Lorida Local was exactly a symbol of this otherworldly reality surrounding the JMSDF submarines. Utilizing stealth and submersible capability to infiltrate the coastal areas of the “Romeo” mainland, they collected topographical data of the coasts and seabed, radio waves, signal intelligence, vessel traffic conditions, fleet movements… any and all information conceivable, and brought it back to Japan. A covert intelligence-gathering mission, its very existence a secret… Commander Ninohe pondered—but was this really any different from that Cold War era when Japan, having played a part in the liberal bloc in the old world, fiercely competed with the socialist powers of neighboring Russia and China?

“Captain, we have reached the scheduled surfacing time.”

“Understood.”

He turned to the control room and stood before the periscope. He flipped the sun visor of his cap, embroidered with the ship’s number and insignia, to the back.

“Sonar, any suspicious propulsion noises in the vicinity?”

“No propulsion noises in the vicinity. It’s completely quiet.”

Commander Ninohe nodded.

“Surface to periscope depth. Standby to activate the electronic warfare support measures system.”

There was no physical sensation of motion. Yet with his single command, the ship gradually began to rise. In the tactical information/weapon control section occupying the right half of the control room, the ESM console operators stared at their dedicated monitors with tense expressions.

“Control room to Captain, ESM system activated!”

“Good…”

The periscope slid up silently, and Commander Ninohe grasped the handles.

“————”

Through the periscope, switched to the infrared image display for nighttime use, the outline of the black coastline was projected before Ninohe’s eyes. The scene of the outside world peering through the periscope was no longer the exclusive property of the captain viewing it directly through the scope. The officers stationed in the control room also watched the images from a dedicated terminal installed there, holding their breath. Ninohe pressed the distance-measuring laser emission button as he swept the periscope around in a full circle. He was gauging the distance from the ship to the coastline, grasping the topography of the enemy territory. Meanwhile, in the tactical information control section, dedicated operators with tense expressions stared at the control terminals for the ESM system and the radar warning receiver, both also operating at periscope depth. The role of the radar warning receiver, which detected enemy search radar waves, was especially crucial for the vessel’s defense. Operating within enemy territory naturally meant there was a risk of being caught in the enemy navy’s patrol net. The Maritime Staff Office’s analysis was that “Romeo”—the Loridan Navy’s—anti-submarine warfare capability was significantly lagging behind that of the JMSDF, but even so, unthinkable events were still possible. And there was absolutely no guarantee, no matter where one looked, that such events would not happen to them.

“Dive. Depth 20.”

The time elapsed was a mere 30 seconds—having completed one sweep, Ninohe folded the periscope handles. The housed periscope body sank downward, and the ship, too, returned to the darkness. Previously, in the same sea area, a sister ship also engaged in intelligence-gathering had reportedly succeeded over a week of on-station operations in intercepting detailed communication records of enemy air force bombers. The Republic of Lorida, or “Romeo,” was overwhelmingly inferior to Japan in conventional military strength, yet even so, they possessed elements where they excelled overwhelmingly. “Romeo’s” other aspect as a nuclear state, inadvertently revealed during the course of the Sloria Conflict, remained a factor that three years after victory in that conflict still divided Japanese national opinion regarding nuclear possession and kept the Japanese people from easing their vigilance against them. The long-range bomber forming one wing of Lorida’s nuclear forces—bearing a nose reminiscent of America’s B-29 long-range bomber from the old world and swept wings suggestive of Russia’s Tu-95 “Bear”—had in fact been deployed at the end of the Slorian War, carrying a nuclear bomb in its fuselage to “suppress” a civilian rebellion that had erupted in the colony of Nodocor. That very fact was the basis upon which the Ministry of Defense’s intelligence division prioritized grasping the movements of this aircraft, Lorida’s strategic bomber… For who but God could guarantee that one day, it would not come flying over Japanese skies with dangerous cargo in its belly? Indeed, the recent existence of a newly deployed aerial refueling aircraft converted from the same model had further strained the already sensitive nerves of the Defense Intelligence Headquarters (DIH).

“Change course. Heading 2-6-3. Maintain speed 6 until reaching the loitering area. Next scheduled broadcast time will be 2035 hours.”

“Aye—”

After announcing he was going to rest, Captain Ninohe turned to head back to the chart room, the navigation officer repeating the orders behind him. In reality, the batteries still had enough capacity that they wouldn’t need to raise the snorkel for recharging at the scheduled time, but he wanted to err on the side of caution. According to the plan, the Kenryū would conduct intelligence-gathering operations in this area for four more days. This was within enemy territory. No one knew what might happen during that time—

Day 21 Month 10; 03:45 Japan Standard Time

Airspace 500 kilometers northwest of Hokkaidō

“Aslan, revised estimated time of enemy contact. Next 57.”

“Aslan, roger…”

Overlapping with the echo of her breathing inside her oxygen mask, she heard the voice of the flight leader communicating with the interception controller. It was by no means a voice trembling with tension before an encounter with the enemy. Yet, if she herself were in the same position as him, the pilot that she was could not imagine herself behaving as calmly as he did.

Total darkness surrounded her. The only outside world visible to the naked eye through the cockpit canopy was the outline of a sea of clouds, illuminated by faint starlight and emerging like an ink wash painting. In these conditions, unless she kept her eyes fixed on the reference lines displayed on the HUD, she couldn’t even tell if her own aircraft was banking. At times, the physical sensation crept in that her plane might be assuming an incredibly dangerous attitude, hurtling down a trajectory toward a crash. Even so, the instruments, switched to night display mode, silently informed her that she was flying the course directed by the ground controller—trust the numbers on your instruments over your own senses, something that had been drilled into her to the point of disgust by instructors throughout her flight training…

I’m scared!

“——…——…——………——”

She listened to her own breathing in her earpiece. Her respiration growing erratic, First Lieutenant Aoi Endō, pilot of a JASDF F-15J Eagle mainstay interceptor now turning in accordance with the flight leader, endured alone the terror of racing through the pitch-black night. The Eagle flown by Flight Leader Captain Takuma Saotome, flying ahead to her right, was now recognizable to her eyes only as a black shadow pushing through a corridor of gray clouds, save for the red and green identification lights blinking at its wingtips.

Endō had been assigned to the 203rd Tactical Fighter Squadron, subordinate to the 3rd Air Wing of the Northern Air Defense Force, the previous month. After completing the advanced flight training course with the modified T-4 intermediate trainer, she had finished extended training on F-15J operations at Nyutabaru in Miyazaki Prefecture—a perfectly natural starting point for a JASDF fighter pilot. But her assignment to the 203rd TFS, a battle-hardened fighter unit that had distinguished itself in the so-called “Sloria Conflict,” surprised her not a little and secretly thrilled her. Regarding the Sloria Conflict three years prior—the operation officially referred to within the government and the Self-Defense Forces as “Operation Slorian Storm”—there was no one who would not name the JASDF as the organization that made the most vital contribution to Japan’s victory. From the initial strike at the very start of the war, which committed half of the nation’s attack aircraft, the combination of high-performance aircraft and precision-guided munitions employed extensively throughout the operation exerted unexpectedly devastating power in attacks on key enemy ground force targets, greatly contributing to the smooth advance of friendly ground units. In the brief fighting that lasted just over two weeks thereafter, the PKF-ASDF Sloria Expeditionary Air Wing flew over 500 combat sorties, destroyed more than 1.200 fixed ground targets and approximately 800 enemy combat vehicles, annihilated around 300 enemy military aircraft on the ground, and moreover, in around 20 aerial engagements large and small that occurred during that period, shot down 72 enemy aircraft with zero losses… As far as the air war was concerned, the JASDF had concluded the Sloria Conflict in a literal crushing victory. At the time, First Lieutenant Endō, a freshly graduated officer cadet from the National Defense Academy, was a student pilot with a flight training unit at Ashiya in Fukuoka Prefecture, where she witnessed the exploits of senior pilots and felt a thrill of excitement as she projected her own future hopes onto them.

“Aslan, climb to Angel 30 (30.000 feet).”

“Aslan, roger.”

The flight leader’s climb—Endō was a moment late in following it. Not wanting to open up the distance, she instinctively pushed the throttle further than the proper value.

—Prrrrrrrrr! …Prrrrrrrrr!—

“………!?”

Proximity warning! Hearing the verdict handed down by the alarm devices placed throughout the Eagle to a rookie pilot who had closed in too much, her left hand gripping the lever reflexively pulled the throttle back, swinging like a pendulum. The distance only grew wider instead—

“Zero-Two, don’t overexert yourself. Just maintain visual separation, that’s all.”

“…Roger!”

Unbelievable… suppressing the urge to say so, Endō looked up, as it were, at the flight leader continuing to climb alongside her. What kind of eyes does the flight leader have? Or does he have eyes on his back, too?

Captain Takuma Saotome was Endō’s wingman and flight leader. In the 203rd Squadron’s office, when Flight Section Chief Major Sōsuke Nagase had introduced them, her first impression of him was simply a “big, absent-minded guy.” His features might be called handsome, she supposed. Yet, she also got the impression that he himself had abandoned any effort to maintain that from the very start. Even so, partly due to his Aviation Cadet background, Saotome’s career as a fighter pilot was far beyond hers. Above all, Major Nagase and Captain Saotome were, in SDF parlance, “Sloria returnees,” and moreover, were among the mere forty-odd “Ledero Killers” in the entire Self-Defense Forces.

A week had passed since Endō’s arrival when she was summoned to the squadron office, where Major Nagase, his feet propped up on his desk with ill manners, said: “Saotome, this is a cute junior from the National Defense Academy karate club. You take care of her training.”

“………”

It wasn't a hostile look, but Endō immediately understood that his expression said something like, “Er… me?” In fact, since coming under his command, she had never once seen on Captain Saotome that sharp-eyed look characteristic of fighter pilots. Still, as she later learned, Saotome’s skill was exceptionally good even within the squadron. Coupled with that “vacant” appearance of his, his popularity among the Women’s Air Force personnel in rear-echelon duties was rather charming, one might say…

Amidst the expanse of a black sea of clouds, pillars of black cloud spread out below her. No, it was a castle of black clouds. Upon reaching an altitude of 30.000 feet, the dominion of night was overwhelmed by the twinkling stars, and beneath the starlight, the heavens spread their full form before her eyes with clear contours. What Captain Saotome had said was correct. Before she knew it, she realized she was flying at the same distance from him as when they had scrambled from Chitose Air Base. Moreover, once they broke free of the cloud sea, the mental space to attend to her surroundings naturally emerged. The multifunction display terminals added to the instrument panel through repeated upgrades since before the Transference continuously updated the positional relationships of the friendly aircraft that had taken off, via inter-aircraft data link. As long as there was no change in the guidance from the Chitose Control Unit, their two aircraft and the two flying 60 miles to the north of them would now intercept the unknown aircraft.

It was one of the scramble missions that had notably decreased in frequency since the Transference—however, this flight carried a degree of tension far too different to be dismissed as such. In the two weeks since they had taken off like this, intelligence officers dispatched from the Defense Intelligence Headquarters in Tokyo, in addition to Northern Air Defense Force command personnel, had begun bustling in and out of Chitose Air Base. It did not take long for the sight of a C-2E electronic intelligence-gathering aircraft, which had likewise hurriedly advanced from Tokyo, taking off from Chitose Airfield at night and returning from somewhere the following night to become a daily occurrence. Another major change was the sudden increase in the interceptor’s armament, previously limited to the fixed-mounted cannon and a single short-range air-to-air missile. Four AAM-5 short-range air-to-air missiles and four AAM-4 medium-range air-to-air missiles represented the maximum air-to-air ordnance an F-15J could carry, a literal “full load.” In wartime this might be acceptable, but for peacetime border security, it was, in truth, arguably “excessive armament.”

But—

“—I hear that before long, a large force of Lorida’s bombers will come flying into the seas near Japan.”

“—It seems they intend to launch a direct nuclear attack on the Japanese mainland.”

Rumors leaking from the senior officers’ meetings held repeatedly in the command post during this time had spread throughout the entire squadron in the blink of an eye. Yet, not a shred of reporting suggesting the gravity of the situation could be found on civilian television, radio, or newspapers—perhaps that was a sign of how thorough the information control was. And then, the day before the sortie, came another “full load” order…

First Lieutenant Endō and the others had taken off late in the night, just as the tension brewing within the base was nearing its peak.

“————!?”

A new luminous point emerged on the aircraft position display of the MFD. Simultaneously, a circular symbol appeared within the HUD. An indicator showing the position of the unknown aircraft, captured by ground-based warning radars or by an early warning aircraft circling the patrol airspace and transmitted to the interceptors via data link—within that circle, even the numerical values indicating the distance to the target, the target's altitude, and its speed were displayed. By flying so as to align the HUD’s center with the symbol, the Eagle would eventually be able to encounter the unknown aircraft from a superior position.

“Aslan, four more have lifted off from Misawa. Currently holding west off the coast of Aomori.”

“Aslan, roger…”

She instinctively knew they were the advanced F-35Js of the 3rd Tactical Fighter Squadron, based at Misawa Air Base in Aomori Prefecture. The unit had just completed its conversion from the F-2 the previous year, and therefore there was some slight anxiety as to whether it could truly function as an effective force. Misawa also had the 8th Tactical Fighter Squadron, operating the F-15EJ, but over half of its strength was reduced due to IRAN, periodic inspections that also involved partial modifications. That this had to happen at a time like this, of all times…!

“Zero-Two, we will encounter the enemy soon. Keep your head on a swivel.”

“Zero-Two, roger…!”

The HUD indicated that the distance to the unknown aircraft they were heading toward was now less than 10 miles. The F-15J itself was equipped with a radar for searching and tracking enemy aircraft, but it was not used overtly on a scramble intercept mission like this one. In such a mission, the search and tracking of the target were left to the ground control unit, with radar emissions from their own aircraft being employed as a “warning” to the unknown aircraft.

“Aslan, tally-ho visual!”

“————!?”

Where!? The moment she inwardly screamed this, she simultaneously spotted what looked like a string of lights ahead of her. In fact, had Captain Saotome not said it, she might well have missed it completely. It was a disturbance so minute that Endō could barely perceive it. Unless someone told you it was there, there were quite a few things in this world that one could not confirm with one’s own eyes.

Silver wings, glinting as they drank in the starlight… they were large, and there was more than one—a four-ship echelon formation. Rodom-775 strategic bombers of the Loridan Air Force, advancing like dragons ruling the sea of clouds—Ministry of Defense reporting name: “Romeo Bear.”

“Zero-Two, we’ll take the left rear of the formation. Follow me.”

“Roger!”

Saotome’s instruction was calm. As they pressed on, the performance data and specifications of the “Bear” that the intelligence officer had briefed them on earlier at the base raced through Endō’s mind. If the information was correct, the Bear should be equipped with defensive gun turrets in the nose, above and below the fuselage, on the sides, and in the tail. If she carelessly positioned herself behind the enemy aircraft and closed the distance without a second thought—

Closing the distance was easy. After all, they were large aircraft powered by piston engines, however high-output they might be. There was no reason a jet like theirs couldn’t catch up. Strangely, she felt no anxiety about possibly being shot at.

“This is the Japan Air Self-Defense Force. To the unidentified aircraft, you are approaching Japanese territorial airspace. Change course immediately and withdraw from territorial airspace.”

The two aircraft flying ahead issued the warning broadcast. The warning, delivered in Japanese, the New World Common Language, and Loridan… a string of languages, would by regulation be repeated three times. If there was still no response—the eight aircraft, four on each side, would continue flying the same course, pressing straight on toward the Japanese archipelago.

“All aircraft, cleared to use radar.”

“Zero-Two, check eyeball.”

“Roger…”

Following her training—tracing in her mind the procedures drilled into her through countless territorial airspace violation response drills—Endō opened up distance from the lead aircraft and focused her eyes on their surroundings. The fundamental principle of formation air combat was that while the lead aircraft searched for and tracked the target with radar, the wingman would maintain a close-range visual watch. Radar was by no means an all-purpose tool; an enemy aircraft could exploit gaps in the radar search coverage and launch a surprise attack from an unexpected direction. That was a fact Endō herself had experienced, suffering bitter “defeats” in several mobile training sessions conducted by the Tactical Fighter Training Group. Since Operation Slorian Storm, the Tactical Fighter Training Group, which increasingly fielded modified T-4 intermediate trainers that physically resembled the anticipated “Romeo” fighters, was formidable, and the operational units equipped with F-15Js and F-2s had repeatedly suffered defeats against their refined combat tactics. It was widely rumored that, in order to fully commit to their role as the JASDF’s “Romeo” air force, they had recently decorated their squadron office with a “Romeo” air force flag procured from somewhere, and had even made the coloring of their aircraft resemble that of the enemy.

While keeping her peripheral watch, she saw on the MFD two symbols indicating the tracked unidentified aircraft become encircled by seekers. At the same moment, two target symbols appeared on the HUD as well—the instant her lead, Captain Saotome, illuminated the unidentified aircraft with his radar and acquired them. As a result of numerous upgrades, the Eagle’s radar now possessed multi-target simultaneous tracking and engagement capability it had not originally had. Furthermore, the tactical information from that process was shared via the inter-aircraft data link with her aircraft, the wingman. A “tactic” was even possible where, if Endō pressed the missile launch button in this state, the launched missile would follow Saotome’s radar guidance, fly straight toward the enemy aircraft, and strike it directly… This, too, was one of the reasons why military personnel in this other world called the F-15J Eagle “the world’s strongest fighter.”

Endō’s hand reached for her helmet visor, and she lowered the filter for aiming the AAM-5 short-range air-to-air missile. Simultaneously, the Helmet-Mounted Display activated, and before her eyes, the two enemy shadows being tracked were encircled by circular aiming reticles. That was the minute movement of the infrared seeker in the nose of the AAM-5, tracking the enemy shadows and refusing to let them escape—so long as she kept her eyes fixed on the targets, she remained in a constant posture to attack them.

“Will the enemy respond?”

Endō’s doubts were twofold. Even under radar illumination, was the enemy seriously intent on intruding into the Japanese mainland? Or, was the enemy even aware that they were being painted by radar?—In either case, the next step they were to take was already decided.

“Unknown, still not changing course.”

“All aircraft, cleared for warning fire.”

The unidentified aircraft banked. Endō pulled back on the throttle to maintain distance from them. The echelon formation entered a sharp left turn, and the interceptors following them did the same. Still, the unidentified aircraft could not escape the radar waves emitted by the lead aircraft, nor did they seem to have any intention of doing so.

“Confirmed change of course by unknown. They appear to be withdrawing from territorial airspace as is.”

She saw the unidentified aircraft lower their noses slightly. Endō thought they had entered a descent to recover the speed visibly lost as a result of the turn. The distance began to widen again—yet the Eagles continued on, keeping them locked on radar, and both sides proceeded beyond the Air Defense Identification Zone.

“Unknown, departing territorial airspace.”

“Aslan, return. Angel 27.”

“Aslan 01, roger.”

“Aslan 02, roger.”

Saotome’s aircraft rolled into a bank, losing altitude as it went… Following the inverted silhouette of the Eagle with her eyes, Endō performed the same maneuver as her lead. Following guidance, they entered a corridor, and if they flew another thirty minutes, threading through the sea of clouds, the two aircraft would cross the coastline of Hokkaidō from which they had come. On their way back to the base at Chitose, they would look down upon the full expanse of Hakodate city to their right…

“—Beautiful…”

“Zero-Two, what is it?”

“No… nothing.”

A flickering torrent of light, as if jewels had been crammed into a rectangular box of darkness—the city of Hakodate continued its nocturnal life, seemingly utterly oblivious to the tension the two had faced in the distant sky until just moments ago. That’s right… it was to protect that city that she had, until just a short while ago, been enduring solitude in the far-off sky.

“Zero-Two, fuel count. I have 1.000.”

“Zero-Two, fuel remaining… 870.”

“You’ve used quite a bit. You land first. Approaching landing course… Aslan, break… now!”

Flying ahead to her right, Saotome reduced speed, yielding the lead to Endō’s aircraft. Before Endō, now in the lead, the runway at Chitose, beginning to twinkle to welcome the Eagles that had fulfilled their mission, was starting to reveal its full length at the edge of the pitch-black land. As she continued the operations necessary for landing, something welled up in First Lieutenant Endō’s eyes. She felt it was a slackening of tension, born of the relief that she could return.

Day 21 Month 10; 03:34 Japan Standard Time

Miho Signal Intelligence Station, directly under the Intelligence Headquarters, Sakaiminato City, Tottori Prefecture

“Report from the radar site. Unidentified aircraft has left the Air Defense Identification Zone. They are currently still flying northward.”

One portion of the split-screen information display terminal showed, in real time, the deployment of Maritime and Air Self-Defense Forces stretching from the Sea of Japan to the waters around Hokkaidō. They had sprung into motion at the same moment the communications station began its tracking, and the number of symbols indicating the locations of operational units was still increasing. The station commander’s eyes were fixed on a blinking point of light in the Sea of Japan. A mobile beacon transmitting guidance radio waves to enable the unidentified aircraft—bombers—to penetrate Japanese airspace on a proper course. The suspicious vessel was now acquired by a JMSDF patrol plane, and was being shadowed by a destroyer that had rushed belatedly to the scene.

“Imagery from the patrol plane is being transmitted. Shall I put it up?”

“Go ahead.”

The video uploaded to the commander’s dedicated terminal captured, in sharp infrared imagery, the clandestine vessel’s appearance as it was approached by the patrol plane and turned its course northward. The violent churning of its wake as it fled through the rough waves of the Sea of Japan was not that of an ordinary deep-sea fishing boat. By now, Intelligence Headquarters in Tokyo was likely in a frenzy analyzing it.

“Komatsu 306, returning to base.”

The two F-2s launched from Komatsu Air Base in Ishikawa Prefecture had been a bluff against the spy vessel. How must it have felt to witness fighters, armed with anti-ship missiles, passing directly overhead of one’s own ship? If the tactical situation displayed on the terminal was correct, the “Romeo” bombers had already set their course homeward toward their homeland, and the clandestine vessel would ultimately slip outside Japan’s territorial waters. Whether it had been an operational maneuver with clear offensive intent, or a show of force… whatever the intentions of the Loridans had been, it was certain that their plans had fallen apart during the night.

Glancing sideways at the deputy commander standing by, the commander spoke. “It’s already been half a year since you came here, hasn’t it.”

“Now that you mention it… yes, it has.”

“Have you been going home to see your family?”

“Regrettably… not once since I took up this post.”

The commander gave a wry smile at the deputy commander, who hung his head awkwardly.

“Go home. I’ll grant you leave… how about this weekend?”

“Is that all right?”

The commander nodded. The deputy commander’s voice brightened as he continued.

“This Sunday… my daughter has a sports day.”

“Is that so… perfect timing, then.”

The commander, too, pictured the face of the son he had left at home. The elementary school his son attended had already held its sports day the week before. The enterprise of national defense forces upon those engaged in it sacrifices that can never be compensated. Yet he believed it was also a fact that those sacrifices saved a greater number of lives. Whether his own conviction was correct was a matter to be pondered on another occasion. At any rate, this night, the threat to Japan had been removed. This confrontation between themselves and the other side, the full extent of which would never be made public—the tension that had been present until just moments before, too, was merely a commonplace scene among the countless such days of confrontation they had experienced.

The commander summoned an orderly.

“Coffee. Get us some, would you? Two cups. With plenty of milk and sugar cubes.”

The electronic space was regaining the tranquility it ought to have. Being at home, a father thinks of the sleeping face of his child, lost in peaceful slumber.