Chapter Text
The morning light is pale and watery when Arisu walks through the school gates, and for the first time in years he doesn’t feel like he’s dragging a corpse behind him.
He’s hungover but not from alcohol—from yesterday. From the exhilarating shock of Chishiya’s smile, from the warmth of his hand, from the way those dark eyes had looked at him like he was something worth solving.
Arisu hasn’t slept properly in months. Last night, he lay awake staring at his ceiling, replaying the moment over and over: Chishiya’s glee hidden beneath that flawless mask, the quiet challenge in his voice.
“Then I suppose I’d better let you try.”
Arisu grins at nothing. A girl walking past him flinches.
He finds Chishiya at his locker, and the sight of him makes something in Arisu’s chest ignite—that strange, hungry thrill he’s been chasing his whole life. Chishiya is wearing his uniform like a costume, perfectly pressed, perfectly indifferent, completely unaware that he’s about to have his morning disrupted.
“Arisu.” Chishiya doesn’t look up from his locker. His voice is dry, amused. “I was wondering when you’d show up.”
“Miss me?”
“I was hoping you’d forgotten.” Chishiya finally glances at him, and there’s a glint in his eyes that makes Arisu’s pulse skip. “That would have been funny.”
“Sorry to disappoint.” Arisu leans against the locker next to his, close enough to catch the clean scent of soap and something else, something warm that he can’t quite name. “I’m here to walk you to class. Very boyfriend-like, very devoted.”
Chishiya raises an eyebrow. “You don’t even know what class I have.”
“I’ll figure it out.”
“You don’t know my schedule.”
“I’ll steal it.”
Chishiya laughs—a real laugh, quiet and surprised, like he didn’t see it coming. The sound does something dangerous to Arisu’s stomach.
“You’re insufferable.” Chishiya says, but he’s smiling. “Fine, walk me to class. Try not to cause a scene.”
“No promises.”
The class Chishiya leads him to is in the west wing, a part of the school Arisu has never bothered to explore. The room is smaller than the regular classrooms, with only about fifteen desks arranged in a semicircle around a gleaming whiteboard. The students filing in are all wearing the same expression, focused and intense, competitive.
Arisu can feel the IQ in the room and it makes him want to yawn.
“Advanced Theoretical Mathematics.” Chishiya murmurs, sliding into a seat by the window. “Are you sure you want to stay? You might hurt yourself.”
“Worried about me?”
“Just don’t want to have to explain to the paramedics why my boyfriend passed out from the sheer intensity of calculus.”
Arisu snorts. He drops into the seat next to Chishiya, sprawling with intentional carelessness, and watches the rest of the students trickle in. They all notice him. They all stare. He can see the whispers starting, the curious glances at Chishiya, the silent question: who is that?
“Last chance to run.” Chishiya says, not looking at him.
“I don’t run.” Arisu props his chin on his hand, grinning. “I’m here to support you. Very romantically. The other students should be jealous.”
“Of you?”
“Of us. We’re the new power couple.”
Chishiya’s lips twitch. “You’re insufferable.”
“You said that already.”
“It bears repeating.”
The teacher arrives, a thin man with glasses perched on his nose and chalk dust on his sleeves. He sets down his briefcase and starts the lesson.
For fifteen minutes, the teacher speaks about advanced theorems, Arisu understands none of it—but he watches Chishiya. The way he taps his pencil in a delicate rhythm, the small almost-smile he gives at a particularly difficult proof.
Arisu feels the hunger rise in him, this terrible, wonderful fascination—like looking at a locked door and knowing there’s something beautiful behind it.
Suddenly the teacher pauses, eyes narrowing at Arisu.
“You.” The teacher points. “You’re not in this class.”
There’s a collective turn of heads. The other students stare at Arisu with a mix of amusement and irritation, as if they see him as a stray cat that’s wandered into their pristine laboratory.
“Caught me.” Arisu says cheerfully.
“Out.”
“I’m supporting—”
“Out.”
The students laugh. It’s not mean, exactly, but it’s condescending—that particular brand of laughter from kids who think they’re smarter than everyone else. Arisu feels his skin prickle with irritation, with the familiar urge to provoke.
“You’re right.” He says, polite and reckless in equal measure, standing up slowly. “I’m not. But I’d like to stay. How about a deal? One question. If I get it right, I sit back down. If I don’t, I leave and never darken your advanced threshold again.”
The teacher’s eyebrows rise. The students exchange glances.
Chishiya goes very still, all his focus pinned on Arisu.
“This is advanced theoretical mathematics.” The teacher says dryly. “You wouldn’t be able to—”
“One question.”
The teacher studies him for a long moment. Then he smiles—a thin, amused smile that says this will be fun.
“Alright.” He turns to the blackboard and picks up the chalk. “Let’s see what you’ve got.”
He writes for a full minute—a complex equation involving multidimensional spaces and what feels like invented symbols, something that makes Arisu’s eyes water just looking at it. The students lean forward, curious. Chishiya’s expression doesn’t change, but his pencil stops tapping.
“There.” The teacher steps back, and he’s grinning a little.
The class goes silent.
A few students are clearly trying to work it out mentally, their foreheads furrowed. Someone mutters “that’s impossible” under their breath.
Arisu looks at the board.
But then, something strange happens.
The noise in his head—the boredom, the restlessness, the anger, the constant itching under his skin—falls away.
The equation stops being a wall of symbols and becomes a pattern, a puzzle, a game. He sees the structure of it, the elegant solution hiding beneath the chaos.
He’d forgotten how good this felt. The click of understanding, the rush of mastery.
He picks up the chalk. The class watches.
Chishiya watches.
Arisu writes.
His hand moves confidently, filling the space beneath the teacher’s scrawl. He writes like he’s been speaking this language his whole life—because he has, he just stopped listening to himself.
When he finishes, he sets the chalk down and steps back.
A stark silence fills up the classroom.
The teacher stares at the board, his mouth slightly agape. The students stare at Arisu like he’s just pulled a rabbit out of his own skull, someone whispers “holy shit”.
Arisu shoves his hands in his pockets, heart pounding with something that feels dangerously close to joy. He looks at Chishiya—
—and Chishiya is looking at him like he’s seeing him for the first time.
There are no traces of his usual boredom or amusement, no, he’s interested. His eyes are bright, his lips parted just slightly, his cheeks faintly flushed, he looks like someone who’s just discovered a new species and wants to dissect it.
Arisu’s heart hammers away in his chest.
The teacher clears his throat.
“That’s—” He pushes his glasses up. “That’s correct.”
Arisu smirks. “I know.”
The teacher looks at him for a long moment, then shakes his head. “Fine, you can stay.”
Arisu grins. He walks back to his seat with a swagger he doesn’t have to fake, dropping into the chair next to Chishiya and leaning in close.
“Told you.” He murmurs. “I’m devoted.”
Chishiya’s lips curve. His voice is low and rough-edged, like he’s just run a mile.
“Where did you learn to do that?”
“I watched a YouTube video.”
Chishiya snorts quietly. “Liar.”
“Maybe.” Arisu’s grin sharpens. “Maybe I’m just full of surprises.”
Chishiya’s breath catches. Arisu hears it, the tiny hitch, sees the way his fingers tighten around his pencil. The satisfaction that floods through him tastes almost better than solving the equation.
“Stay.” Chishiya says quietly. “I want to see what else you can do.”
The day unfolds like a flower he didn’t know he was growing.
Chishiya is not used to being surprised. He has his routines, his perfectly calibrated systems. He knows how people will react before they react. He knows what they’ll say, what they’ll do. How they’ll disappoint him.
Arisu is a variable he can’t predict.
He shows up at Chishiya’s locker with that grin—that infuriating, exciting grin—and Chishiya feels something in his chest crack open like an egg. He’s not used to this, not used to someone choosing him, to someone showing up just to see him.
And then he stays.
The advanced mathematics classroom is Chishiya’s territory, the one place where he’s supposed to be the smartest person in the room. It’s a comfortable, unchallenging position. The other students look at him with envy and respect in equal measure, with the desperate hunger of competition. Chishiya finds them all tedious.
Then Arisu sits down next to him and Chishiya realizes he’s been bored for years.
He watches Arisu during the lesson. He watches the way his eyes glaze over when the teacher talks, the way he slumps in his seat like he’s not even trying to pay attention. Chishiya doesn’t mind. He’s used to being surrounded by people who don’t understand what he’s saying.
But then the teacher calls Arisu out, and the class laughs, and Chishiya should be amused—he is amused—until Arisu’s jaw tightens and something shifts in his expression. He stands up, and Chishiya sees the fire in his eyes, the desperate hunger for something more.
Chishiya’s heart does something concerning.
He watches Arisu pick up the chalk, watches his hand move across the board, fast and sure, writing symbols that shouldn’t make sense for someone who’s supposed to be a slacker, a troublemaker, a boy who gave up on school years ago.
But Arisu isn’t giving up. He’s solving.
The solution is beautiful. It’s better than anything Chishiya could have come up with, and that’s—that’s incredible.
He’s so focused on the board that he forgets to breathe. When Arisu turns around, when their eyes meet, Chishiya feels something hot and fierce surge through him, a wave of want so powerful it nearly knocks him over.
Arisu is brilliant.
And he’s looking at Chishiya like he’s the only person in the room.
The teacher lets him stay. Arisu sinks back into the seat next to Chishiya, close enough that their shoulders touch, close enough that Chishiya can feel the heat radiating off his skin.
Arisu’s voice is low and smug and gorgeous.
Chishiya wants to kiss him. He wants to grab his collar and pull him close and—
He doesn’t. He keeps his composure and files the foreign impulse away for later.
Instead, he leans in just enough that only Arisu can hear him.
Arisu turns his head. Their eyes meet and hold for a beat too long. Something electric and unspoken passes between them in the narrow space, sharp enough that Chishiya feels it in his teeth. Then Arisu’s mouth curves, soft and a little dangerous, and he faces forward again as if nothing in the world has shifted.
Lunch is a bloodbath.
Not literally—Chishiya’s fairly certain no actual casualties have occurred. But the dramatic declarations of despair coming from the table beside them are enough to make a boy consider switching schools.
He watches, idly amused, as one of his regular admirers presses a hand to her chest and actually gulps when Arisu leans over to steal a piece of tamagoyaki off Chishiya’s bento.
“Your food is better than mine.” Arisu says through a mouthful of omelet. “Way better. What is this, gold leaf?”
“That’s expensive.” Chishiya says flatly. “Stop stealing it.”
“But I’m your boyfriend.”
In the corner of his eye, another admirer whimpers.
Arisu’s face is innocent, but his eyes gleam with mischief, and Chishiya understands what he’s doing—playing the part, reveling in the chaos, using their proximity to drive the knife deeper into the hearts of his fan club. It’s the same wild, reckless energy that got Arisu thrown out of more classrooms than Chishiya had been able to count.
But there’s something else, too. A glimmer of real warmth in those dark eyes, genuine enjoyment in the act of doing this, with him.
Chishiya tries to figure out why he doesn’t mind it. Why, in fact, he finds himself liking this—the attention, the way he’s no longer sitting alone at a table surrounded by people who never ask him anything real.
“You’re feeding me.” He observes, when Arisu holds up another piece of omelet.
“I’m being affectionate.” Arisu corrects, nudging the bite toward Chishiya’s mouth. “Say ‘ah’.”
“Absolutely not.”
“Say ‘ah’.”
“Arisu.”
“I’m trying to be a good boyfriend, Chishiya. Don’t be difficult.”
The stare-off that follows is interrupted by a sniffling sound from the neighboring table. Chishiya’s gaze travels over. One of his most devoted admirers—the girl who leaves him notes in his locker every morning, who once tried to knit him a sweater—is watching them with teary eyes and a trembling lip. A quiet, desperate “no” escapes her.
Arisu looks at Chishiya. Chishiya looks at Arisu.
And then, Chishiya, mostly to see the look on her face, accepts the piece of omelet directly from Arisu’s chopsticks.
The gasp that ripples through the cafeteria is so loud that even the table of basketball players looks over.
“That was cruel.” Arisu whispers, though his grin is delighted. “You’re enjoying this.”
“You have no evidence of that.”
“You made a girl cry.”
“She cries pretty often. It’s her aesthetic.”
Arisu laughs, a genuine, full-bodied sound that seems to catch even him off guard. Chishiya watches the way his eyes crinkle, the way his hand goes to his chest like he’s physically feeling the laugh. Something in Chishiya’s chest pulls, lazy and warm.
“You know.” Arisu says, settling back into his seat. “I expected you to be weird about this.”
“About pretending to date you?”
“About having to actually talk to me. About being seen with me.” Arisu’s grin fades a little, replaced by something quieter. “I’m not exactly the school’s favorite person.”
“Why would I care what the school thinks?”
“I don’t know. You seem like you care about your image.”
“I care about my reputation.” Chishiya picks up his chopsticks again. “There’s a difference. My grades are a product of efficiency, not ego. And my reputation keeps people from bothering me with emotion, which is a service I appreciate.”
“Hmm.” Arisu tilts his head, considering him. “So you don’t care what anyone thinks of you?”
“I care what I think of me.” The words come out sharper than Chishiya intended.
Arisu blinks, and for a moment the amusement fades from his face.
“Yeah.” Arisu says quietly. “I get that.”
The table falls into a comfortable silence. Chishiya takes another bite of food, deliberately not thinking about the way Arisu’s voice softened just then, about the flicker of understanding in his eyes.
The final bell sends the school spilling out in a messy flood of bodies and noise. Arisu falls into step beside Chishiya without asking, hands in his pockets, matching his pace like it’s the most natural thing in the world. Students part around them, phones tilt and whispers follow like a second shadow but neither acknowledges the attention. They’re both too busy measuring the space between their shoulders, the way it keeps shrinking without either of them meaning it to.
They reach the school gates, though the usual black car isn’t waiting there. Chishiya’s phone vibrates once and he glances at the screen, then slips it back into his pocket.
“Driver’s late. Traffic.”
Arisu nods and doesn’t leave. He leans against the low stone wall just outside the gates, close enough that their arms almost brush. The afternoon light is soft, catching on the silver strands at Chishiya’s temple, on the faint shadows under his eyes that no one else seems to notice. Students stream past them, a few slow down. Someone openly lifts a phone. The air feels tighter than it should.
Arisu’s pulse is already climbing. The hunger hits him all at once—sharp, sudden, almost physical. He’s spent the whole day watching Chishiya, cataloguing the dry remarks, the rare genuine smiles, the way competence and boredom and a quiet fire live under that perfect mask. Now the day is ending and he doesn’t want it to. He doesn’t want the game to pause. He wants more. He wants closer.
The thought hits him like a freight train.
“I want to kiss you.” Arisu blurts out.
The words hang in the air like a struck bell.
Chishiya freezes. His whole body goes still. For a long fistful of seconds he doesn’t react at all. Then his eyes narrow, and that familiar, mocking smile curves his lips.
“What was that?” He asks, and his voice is low, teasing. “You want to what?”
Arisu’s face heats. He wants to take it back, but he also doesn’t. “I said I want to kiss you.”
“Hmm.” Chishiya tilts his head, studying him like a specimen under a microscope. “I see. So the great Arisu Ryohei wants to make things even more complicated. That’s very on brand.”
“Are you going to let me?” Arisu doesn’t mean to sound so desperate, but the words come out rough and he can’t read Chishiya’s expression.
“No.” Chishiya says simply.
Arisu blinks. “What?”
“I said no.” Chishiya’s smile sharpens. “You can want all you like, but you’ll never do it. You’re too much of a coward, aren’t you? You’ll talk a big game, but when it comes to actually following through—to risking something real—you’ll find an excuse to run off and hide.”
The taunt is good, precise. It’s exactly the kind of needle that Chishiya uses to poke at people’s weaknesses—and it works.
Something hot flares in Arisu’s chest, but it’s something other than anger, something worse. Something hungry.
“You think I’m a coward?”
“I think you’re all talk.” Chishiya’s eyes are glittering, daring him. “Prove me wrong.”
Arisu’s heart is trying to beat out of his chest. He knows what Chishiya is doing. He knows this is a game, another move on the board, meant to provoke him into acting. And he should probably be annoyed. He should probably laugh it off, call Chishiya out, walk away.
Instead, he smirks.
“You really want me to?” He asks, and his voice has dropped into something low and a little malicious.
Chishiya’s mask slips for a second. Something sparks to life in his eyes. Surprise, maybe. Delight. He recovers quickly.
“Go ahead.” He says softly. “I’m waiting.”
“Watch me.” Arisu murmurs.
Then he kisses him.
Their lips collide, messy, uncoordinated, electric. Arisu’s hands come up to cradle Chishiya’s jaw, tilting his head. Chishiya makes a small sound against his lips, and then his hands come up, one tangling in Arisu’s hair and the other gripping his shoulder, pulling him closer. He kisses back with just as much force, and all the air in Arisu’s lungs disappears.
They’re at the school gates. Students stop walking, someone gasps, phones rise higher; none of it matters. Arisu feels Chishiya’s tongue brush his lower lip and opens for him without hesitation. The kiss deepens, turns almost fierce. Chishiya tastes like the tea he drank at lunch and something cooler underneath, something that makes Arisu’s knees threaten to give. He presses closer, crowding Chishiya back against the stone wall, and Chishiya lets him, meets him, challenges him, kisses like he’s been waiting for exactly this kind of fight.
They lose seconds, maybe more. When they finally break apart it’s only far enough to breathe. Their foreheads almost touch, their lips are swollen. Both of them are breathing hard.
Arisu’s hands are on Chishiya’s face. Chishiya’s fingers are tangled in his hair. Neither lets go.
Chishiya’s eyes are wide, dazed. His mask is completely gone.
“That was—” Chishiya starts, and his voice cracks.
Arisu laughs, breathless. “What?”
“You.” Chishiya’s hand is still in his hair. His fingers curl slightly, almost involuntarily. “You actually did it.”
“I told you.” Arisu says. “I’m not a coward.”
Chishiya’s breath comes out shaky. The sun catches his eyes, and Arisu sees something there, a wet gleam, an emotion he can’t name.
Chishiya’s pulse is still thudding hard in his throat. He can taste the kiss—fierce, unrestrained, nothing like the careful performances he’s used to. His fingers are still curled in the fabric of Arisu’s blazer, in his soft hair; he forces them to loosen one by one.
He should say something cutting, something that puts the proper distance back in place. Instead his gaze drops, briefly, to Arisu’s mouth, and the truth slips out quieter than he intends.
“Don’t start something you can’t finish, Arisu.”
Arisu’s eyes are too bright, too alive. The smirk that answers is softer around the edges than usual, but no less dangerous.
“Who says I can’t?”
A black car turns the corner and slows toward the curb. The driver’s window is already lowering. Chishiya feels the ordinary world trying to reassert itself—the distant chatter of remaining students, the low idle of the engine, the knowledge that in thirty seconds he’ll be behind tinted glass and the day will be over.
He doesn’t move yet.
“...I was so bored before you.” He admits in a whisper, almost to himself, the words devastating in their honesty.
Arisu’s expression shifts, something raw and startled flickering across it before the familiar reckless grin settles back into place, a little dimmed.
“Yeah.” He answers, softer than Chishiya has ever heard him. “Me too.”
The car door opens. Chishiya finally steps back, but not before straightening Arisu’s collar with careful fingers. The gesture is almost tender. Almost possessive.
“Don’t be late tomorrow.” He says, soft and mean and full of promise. “Boyfriend.”
Arisu watches him walk to the car, heart still racing, lips still tingling, the gray world suddenly vivid and wide open in front of him.
He grins to himself.
“Wouldn’t dream of it.”