Chapter Text
The sun in July did not just shine; it was heavy.
It pressed down on the back of Rin’s neck like a heavy, damp hand, gluing his dark greenish hair to his skin as he dragged his final duffel bag up the narrow concrete stairwell of the apartment complex. The stairs smelled of hot asphalt and old dust, the air so thick with humidity that breathing felt like inhaling lukewarm water. Somewhere nearby, buried in the parched leaves of an overgrown cicada tree, the insects were screaming: a loud, metallic, unceasing hum that vibrated straight through the soles of his shoes.
He hated the blazing heat. He hated the sound those stupid cicadas made. But out of all those things, he hated his brother, Sae Itoshi, the most.
The apartment was supposed to be a practical arrangement, an inheritance of convenience. Sae had outgrown the small campus space, moving on to a better fellowship, and had passed the lease down to Rin with a flat, indifferent expectation that Rin would maintain it. There had been no advice, no older-brother guidance; just a text message with the banking information for the rent and a brief command to not waste the space.
Rin unlocked the door to Apartment 505, located on the uppermost floor.
The interior was a dark, suffocating box. The air inside had been trapped for days, thick with the scent of boiling asphalt and something that smelled like a trash bag left outside for way too long. Rin didn't drop his bag. He walked straight across the small entryway, sliding open the screen door to the balcony, and cranked down the temperature on the ancient wall-unit air conditioner.
The machine groaned. It shuddered violently, sputtering out a cough of stale, warm dust before its fan finally began to turn with a low, rhythmic rattle. It didn't cool the room; it merely moved the heat around.
Just wonderful. He definitely loved the cloud of old dust that followed right after.
He spent the next two hours meticulously claiming his half of the world. Rin unpacked his clothes into the built-in closet of the left bedroom, folding each shirt with sharp, aggressive precision. On the low wooden desk by the window, he arranged his university texts by height. Beside them, he laid out his notebooks and his single, black 0.5 mechanical pencil-the clicker aligning perfectly parallel to the edge of the desk.
He had a mountain of complex translation theory texts to get through before the autumn semester began. He had convinced himself that if he simply locked his door, kept his eyes on the paper, and ignored the rest of humanity, he could survive the summer in total, frozen isolation.
Then came the noise of the front door clicking open.
Following the click, a dull, heavy thud came right after: the unmistakable sound of a massive, overstuffed cardboard box being dropped unceremoniously into the tiny apartment.
Rin’s hand froze over his notebook. His jaw clenched.
He slid his bedroom door open, his eyes narrowing into cold, freezing hostility as he walked down the short hallway. He was ready to beat the crap out of whoever had decided to walk in uninvited. He realized-with a sharp spike of annoyance-how he had completely forgotten to lock the deadbolt behind him.
Instead, he stopped dead in his tracks.
There was a small figure slumped against the slightly open doorway.
The boy was practically drowning in a box of university textbooks. He was wearing a faded, oversized sports jacket that went past his hands and fell all the way to his mid-thigh. His dark blue hair was damp from sweat, sticking to his forehead in messy clumps. He was breathing heavily, his chest rising and falling in shallow, rapid increments that seemed entirely too heavy for someone who had only walked up a few flights of stairs.
For someone who supposedly played sports, it should have been light work.
"Ah!" the boy gasped, trying to stabilize the weight of the boxes as he let himself in. He offered a small, tentative smile that didn't quite reach his eyes. "You must be Rin. Sae told me I could occupy the second room to split the utility bills. I'm Isagi. Isagi Yoichi."
Rin didn't move. He didn’t walk over to help him carry the boxes. He just stood there, looking down at him.
He cataloged Isagi with a single, sharp sweep of his eyes. Isagi looked... washed out. Under the harsh glare of the hallway’s fluorescent bulb, his skin had a faint, translucent paleness to it, and the shadows under his large blue eyes were a deep violet. He looked like the heat was actively melting him from the inside out.
"I don't care who you are," Rin said, his voice flat, low, and dripping with venom. "Keep to your side of the apartment. Don't touch my things. Don't speak to me."
Isagi blinked. The reaction that Rin might have expected from a fellow university student didn't appear. Instead, Isagi’s shoulders just slumped slightly, a look of profound, quiet exhaustion settling over his face.
"Right," Isagi murmured, his voice trailing off, sounding small and strangely hollow in the tight hallway as he walked to his bedroom. "Just... need to put this down."
He shuffled past Rin, his sneakers dragging slightly against the linoleum.
Rin glared after him, snapping, “Well, take off your goddamn shoes! You’re dirtying the place, you cockroach!!”
He then stormed back to his room and slid the door shut, cutting off the sound of Isagi unpacking across the hall. He picked up his mechanical pencil, pressing the lead against the paper, forcing his mind back into the rigid structure of his translation work.
But by the time the clock struck two in the morning, the paper was completely useless-damp from his hand resting on it for so long in the oppressive air.
The temperature hadn't dropped with the night; it only seemed to grow worse. The apartment remained a sticky, humid greenhouse. Rin leaned back onto his squeaky chair, staring blankly up at the ceiling, his skin damp despite the rattling hum of the air conditioner down the hall.
The silence he had craved was gone, replaced by a strange, hyper-awareness of the thin drywall separating his room from Isagi’s.
Through the wall, the sounds were tiny, but to Rin's fixated mind, they were deafening. He heard the slow, erratic rustle of some sort of paper, followed by a soft, shallow cough. And then, he heard the quiet, dragging footsteps as Isagi slid his door open and walked into the dark kitchen.
Rin stayed perfectly still, his eyes tracking the thin line of yellow light that cut across his bedroom floor from the hallway.
He listened to the refrigerator door open. He waited for the sound of a glass being filled or the sound of a tap running. But there was nothing. Just the low, mechanical hum of the fridge, and the heavy, slightly irregular sound of Isagi’s breathing in the dark kitchen: slow, distant, and completely still.
Rin stared at the crack of light under his door, a sudden, cold prickle of irritation tightening in his chest. He didn't know why, but the absolute quiet coming from the kitchen didn't feel like peace.
It only felt empty.
He closed his eyes and tried to get back to work, tilting his head back down onto the textbook that was still stuck on the first chapter. He silently cursed the summer heat and the stranger who had just bled into his world.
After a few minutes of just the constant, warning chime of the fridge begging to be shut, he decided enough was enough.
What could this psycho possibly be doing at two in the morning, just letting the fridge’s cold air go to waste?
He muttered the thought to himself, grabbed the handle of his bedroom door, and stepped out into the dark hallway.
The kitchen was bathed in a stark, pale blue light slicing out from the open refrigerator door. Isagi didn’t look up when the floorboards creaked. He was just standing there in his oversized jacket, his feet flat against the cold laminate, staring blankly into the illuminated shelves. He wasn't reaching for water; he wasn't looking for food. He was just letting the cool, artificial air wash over his pale face, his unblinking eyes completely hollow and fixed on nothing at all. The heavy, shallow rhythm of his breathing was the only proof he was still there, his skin looking translucent and ghostly under the white light.
"Hey," Rin snapped, his voice a low, dangerous growl in the quiet apartment. "Shut the door. You're wasting electricity."
It took two full seconds for Isagi to react.
When his head finally turned toward Rin, his movements were agonizingly slow, his large blue eyes glazed over with a deep, dissociative fog that made him look miles away. He didn't offer a polite smile this time, nor did he look intimidated by Rin's glare. He just blinked once, a small, shivering breath escaping his lips as he murmured, "It's too hot, Rin... I think the air is swallowing me."
Before Rin could even process the absurdity of the statement, Isagi reached out, weakly clicking the refrigerator door shut and plunging the kitchen back into a heavy, suffocating darkness. He shuffled back toward his room without another word, leaving Rin standing alone in the humid dark, his heart hammering against his ribs with a sudden, uninvited spike of pure irritation.
But it left a faint, terrifying chill he couldn't quite explain-a sickening gut feeling that something about the boy was deeply, fundamentally wrong.