Chapter Text
Jump Force's second non-combat recruit was the polar opposite of Light Yagami in just about every way save for their impressive intellects. Senku Ishigami was loud, brash, and constantly in motion. He sported a tattered lab coat made of crudely-fashioned leather, dotted with stains of all sorts of strange implausible colors. The only identifiable spot on the mess was an "E = mc2" scrawled on the collar in a dark brown that any Jump Force combatant would recognize as dried blood. He had wiry unruly hair that stood straight up from his head like a living creature with its own will. His face was marred with thin lines around his eyes permanently blackened with strange necrosis, but it didn't give him any trouble. He beamed and scowled and rolled his eyes with the best of them.
Socially, Senku was something of an odd man out. Because he couldn't fight, he wasn't a member of any of the three Jump Force teams. Because he was a member of Jump Force but wasn't tied to a particular team, he flitted around the Jump Force headquarters with impunity, butting into conversations whenever he pleased and talking to anyone who caught his interest. Unlike Light, who restricted himself to the briefest possible interactions with the team leaders and otherwise kept to himself for his sanity's sake, Senku had an interest in just about everyone.
His first victim was, as it happened, one of the team leaders. It was only a day after Senku's arrival that he cornered Luffy in a hallway and asked, wide-eyed and intent,
"So, how much of you is rubber, exactly?"
Luffy blinked at him. "All of me." He hooked a finger in his mouth, then stretched his cheek out a full foot away from his teeth. "I'm a rubber man."
Senku leaned in, curiosity oozing off him in waves. "Really? Even your hair and teeth?"
Luffy let go of his cheek. It snapped back into place with a twang like a rubber band. "Who cares?" He screwed up his face. "You're nosy, huh?"
"Yup!"
Senku began to pace, back and forth at first, then in slow circles around Luffy as he chattered. He punctuated his every word with broad dramatic hand gestures and smug self-satisfied laughter.
"You see, back home, we've lost all our rubber. A few thousand years and it all wore away! Can you believe it? We're in Japan, so we don't have any rubber trees on hand, not even in greenhouses—believe me, I've checked—and if I can bring some back, even if it's not much, I could get our electronics working better. You can do a lot without proper insulation, but can you imagine what we could do with rubber? It wouldn't even have to be electronics. We need better food storage. Easy and consistent fluid transportation would be a total game changer. We'd be ten billion times better off, I'm telling you. We're using barrels right now, but we've only got a couple of people who can lug 'em around. We can't all be meatheads like Taiju, y'know? And we've only got a couple wheelbarrows and the roads are still pretty rough, so that's usually a no-go without the car anyway, and there's way too much to do to be using our only engine for whatever..."
Luffy tuned out everything Senku said after a sentence or two. Too complicated; not interesting. He watched Senku pace and, more specifically, watched his hair, which was just about the only thing about him worth paying attention to. Luffy pointed at the green ends of Senku's hair.
"Why's your hair look like that?"
Senku switched tracks without missing a beat. He didn't even pause to take a breath between being interrupted and answering the question.
"Hair dye!" he announced. "It's not as long-lasting or as bright as the synthetic stuff we used to have in stores, but when your hair's naturally white like mine, it doesn't matter so much. I found some leeks growing right near where I came to, which was perfect, because I knew I could eat 'em and there were so many I had enough left over to dye my hair. Grass works too, and it's a lot easier to get your hands on, but it's way too yellow for me, so I used a bit of my food stores. Kinda risky, but ten billion percent worth it, if you ask me. I just had to boil 'em down and..."
Luffy fared no better on the paying attention front the second time around. Within seconds, his eyes were glazing over. He made the executive decision to tune Senku out and continue walking down the hall toward Sanji's kitchen for the good of all Jump Force. He was hungry.
"Wait!"
Senku's hand gripped Luffy's hair tightly. Luffy kept walking. His head stayed behind, held fast by Senku's grip, while his neck extended to allow the rest of his body to carry on. Luffy furrowed his brow at Senku while his neck stretched farther and farther down the hall.
"You're a real pain. I'm hungry. Let go or I'll punch you."
Senku eyed Luffy's hands, which had made it most of the way down the hall. Luffy gave Senku a warning look. Down the hall, Luffy's body stopped and turned around, fist raised in a silent threat.
Senku let go. Luffy's head flew down the hall toward the rest of his body and snapped back into place with ease. The interrogation, though, was far from over. Senku scrambled down the hall to catch up and fell into place by Luffy's side, panting from the exertion of running.
"Your hair doesn't stretch!" he wheezed triumphantly. He reached for one of Luffy's hands. "What about your fingernails? Lemme see."
Luffy grimaced. "Man, you're annoying. Why's it so hard to get rid of you?"
Luffy smacked Senku, gently for Luffy, but with more than enough force to send Senku flying. Getting slammed into the wall hard enough to knock all the air out of his lungs was, thankfully, enough to shut Senku up for long enough for Luffy to make it to Sanji's kitchen in peace.
Senku came back again five courses in to Luffy's lunch. He entered the kitchen with his hands held up in surrender. Luffy glared at him through a mouthful of steak, then another one, then another one. Senku eyed Luffy's mouth with distaste, then curiosity, then shook his head and sidled over to Sanji by the stove.
Senku greeted Sanji with the same long-winded spiel about rubber and technology and yada yada yada. Luffy wouldn't have paid attention to it even if he wasn't eating. Sanji nodded along, and replied when appropriate. His hands kept moving at full speed and without the slightest error, which was good, because Luffy didn't want to have to waste any more energy on punching Senku in order to get more food. On that note, Luffy looked down at his plate and found it empty.
"Sanji!" Luffy shouted. "More food!"
"Yeah, yeah. It's coming! Hold your horses!"
A few minutes of cooking and boring conversation with the leek hair guy later, Sanji was approaching the table with another armful of plates piled high with meat. Senku stayed behind in the kitchen, leaning up against the counter and smirking to himself like he was in on some kind of scheme.
"What's with that guy?" Luffy asked, as he stretched out an arm to grab a fistful of meat from one of the plates Sanji had yet to lay on the table.
"He's a researcher. Lookin' for ways to help out his buddies back home," Sanji replied.
When Luffy's arm came back for round two, Sanji grabbed it. He pulled a knife out of his pocket and shaved off a sliver of Luffy's fingernail. Luffy stared at Sanji, baffled, but didn't object. Sanji held up the fingernail trimming to the light and squinted at it.
"Enjoy the food, Captain. I'll get more cooking for you in a second."
Sanji returned to the kitchen. He held out the fingernail clipping to Senku, who took it with a grin. He struggled to find a good grip on it, then discovered, much to his apparent delight, that it stretched like a rubber band. Senku asked to borrow a small corner of the stove and something to try and melt it in. Luffy shouted that he couldn't have it, reasoning that any interruption would slow down his meal. Sanji shouted, louder, that Senku was free to use anything he wanted as long as he didn't get in the way or break anything.
For lack of anything better to do, Luffy watched Senku and Sanji move around in the kitchen. Before long, Senku was leaned over a small metal pot and marveling that, "It doesn't melt."
"Yeah," Sanji said, juggling his many pans filled with sizzling meats and sauces. "It's not exactly rubber. More like he's got a human body that acts like rubber. His skin burns and he bleeds when you cut him."
"That's unbelievable! What is he made of? His circulatory system must be something else to keep him alive while he's ten meters long."
Sanji shrugged. "Don't ask me, kid. You're the scientist here."
Senku retreated away from the stove. He fished his test subject out of the pot and tucked it into one of his coat's many pockets, then parked himself in front of the sink and got to work on scrubbing the dishes.
"I doubt this'll be much use to me if I can't extract the rubber, but it's some exciting stuff. Given that he's still alive, I'm guessing you've got different physical laws where you're from. If I didn't have a whole world to rebuild, it'd be crazy fun to go to your world and learn it all again from the ground up. Do you even have conservation of mass? I've heard some exciting stuff about what that guy Blackbeard can do..."
Senku chattered away, mostly to himself, though Sanji occasionally came up with something to offer, while Sanji cooked and Luffy ate. Senku managed to get through washing the dishes with remarkable efficiency despite not pausing to stop talking and concentrate even once. When the sink was empty, he turned around, said a casual thanks to Sanji and strolled out of the room with a grin.
Luffy and Sanji watched him go.
"Weird guy," Luffy said.
"Weird guy," Sanji agreed.