[Hirose Residence – Emergency Stairwell ]
The fire door groaned on corroded hinges as Satou Shirou pushed it open.
Darkness swallowed everything past the threshold. The motion-sensor lights along the emergency stairwell had burned out long ago—probably months, maybe longer—and the building management clearly hadn't bothered replacing them. A thick, stale odor of concrete dust and old mildew rolled out from the gap like breath from a sealed tomb, mixing faintly with the residual sweetness of birthday cake frosting still clinging to Shirou's shirt collar. Somewhere far below, a pipe ticked against its bracket in a rhythm that had nothing to do with anyone's heartbeat.
He squinted into the black.
Nothing.
"I've actually lost my mind," he muttered, one hand still braced against the cold metal doorframe. The steel was gritty under his palm, textured with years of neglected grime. "Yoru and Riku in a place like this? Doing what?"
I'm being pathetic. Like some jealous side character in a bad romcom who gets exactly what he deserves.
Shirou shook his head hard enough that his bangs whipped across his forehead. He leaned further in anyway, craning his neck past the doorframe, letting his eyes adjust. The stairwell descended in sharp right-angle turns—poured concrete steps with chipped yellow safety paint on the edges, a rusted handrail, absolute nothing else. No movement. No silhouettes. Not even a rat.
He pulled back into the seventh-floor corridor. Fluorescent light buzzed overhead, washing everything in that flat, institutional white that made apartment hallways feel like hospital wards after visiting hours. Shirou fished his phone from his back pocket, thumb already navigating to Yoru's contact. He pressed call.
Two rings.
Three.
Then—
Puru Puru Puru~!
A ringtone. Bright and electronic, the opening notes of some idol anime OP, unmistakably Yoru's custom tone. And it was coming from inside the stairwell.
A faint rectangle of screen-light bloomed around the corner of the first landing, maybe half a flight down. Blue-white glow against raw concrete.
Bzzz… bzzz… bzzz…
His own phone went to busy tone. Shirou lowered it slowly from his ear.
The busy signal didn't matter anymore. Hirose Yoru's phone had just rung inside a pitch-black emergency stairwell at ten o'clock on the night of her own birthday party.
"Yoru?"
His voice echoed off bare walls, swallowed quickly by the vertical shaft of darkness below.
No answer.
"Yoru, are you in here?"
Silence. Just that distant pipe ticking.
Shirou stepped through the doorway. The fire door eased shut behind him with a pneumatic hiss, cutting off the corridor light and plunging him into near-total darkness. He kept one hand on the gritty handrail and descended carefully, his sneakers scuffing on concrete. Each step kicked up a faint puff of dust he could taste on his tongue—chalk and neglect.
He rounded the landing.
There she was.
Hirose Yoru sat crouched against the wall at the turn of the staircase, knees drawn to her chest, arms wrapped tight around her shins, face buried completely in the dark valley between her kneecaps. Her cream-colored cardigan had slipped off one shoulder. The hem of her pleated skirt pooled on the dusty concrete around her like something wilting. Her hair—loose now, freed from whatever clip had held it during the party—curtained down past her arms in dark waves that trembled with the faintest, barely perceptible vibration.
"Yoru, why are you sitting here alone?"
She's shaking. God, I really did it this time.
I ruined her birthday. I ruined everything because I couldn't keep my mouth shut about Riku and now she's hiding in a stairwell on the night that was supposed to be about her.
Shirou's stomach clenched with the specific nausea of self-inflicted guilt. He crouched down a few feet from her, elbows on his knees, trying to make himself smaller, less threatening. He could smell her shampoo—something floral and light, jasmine maybe—cutting through the stagnant stairwell air.
"Yoru, I'm sorry. I couldn't control myself tonight. That guy Riku, he just—"
"Enough."
Her voice came out fractured. Thin. Shaking at the edges in a way Shirou had never heard before—not in two years of friendship, not in the handful of months since his feelings had started curdling into something desperate and possessive and ugly.
"I don't… want to hear you explain." A breath. Unsteady. "I just need to be alone. For a minute."
"I—"
"What more do you want from me?!"
The words ripped out of her, ragged, almost a scream, ricocheting off concrete in the enclosed space. Her shoulders heaved. Her whole body was shaking now—violently, unmistakably—and Shirou flinched back like she'd struck him.
Beneath her voice, so faint it registered only as texture in the silence that followed, a low mechanical hum pulsed steadily. Bzzzzz. Constant. Almost subliminal. Shirou's ears, ringing from her shout, didn't catch it.
I've never seen her like this. Not once. Not ever.
I did this.
He retreated up the stairs, back to the fire door. Pushed it open. Paused with one foot in the corridor light.
"Yoru… everyone's still waiting for you inside. Whenever you're ready. I'll be here."
"Close… close the door." Her voice had dropped to something barely above a whisper, vowels stretched thin with a quality Shirou couldn't identify. "I just want to be alone. Please."
She said please. That means she's not completely furious. Maybe. Possibly. God, I'm an idiot.
Shirou let the door swing shut. The pneumatic hiss sealed the stairwell back into darkness, and he stood in the fluorescent corridor, jaw tight, hands at his sides, pulse thudding dully in his ears.
He walked to the wall opposite Yoru's apartment door and slid down it until his ass hit the cold tile floor. Drew his knees up. Buried both hands in his hair and pulled.
"Dammit… how the hell did it end up like this?"
Was it the money? The custom cake Riku brought—thirty thousand yen minimum, easy. The way he kept brushing against her arm like it was nothing, like proximity to her was something he was entitled to. Those small, deliberate touches that screamed ownership while Shirou stood there holding a department store gift bag like a supporting character written out of his own story.
But my reaction was worse. Infinitely worse.
Making a scene. Raising my voice. Turning her birthday into a referendum on my insecurity.
Shirou pressed his forehead against his kneecaps and breathed dust and guilt in equal measure.
I'm the worst person in that apartment tonight. And that includes the guy I can't stand.
---
[Emergency Stairwell, Half-Flight Below 7th Floor Landing — 9:53 PM]
The fire door's seal clicked.
Footsteps. Not ascending from the corridor—descending. Soft-soled, deliberate, emerging from the flight below the landing where Yoru crouched. A shadow detached itself from deeper shadow, and Riku's lean silhouette materialized beside her, hands in his pockets, posture loose as a cat stretching after a nap.
Right on schedule.
"Chasing your little boyfriend away like that," Riku said, voice low and warm and absolutely unhurried. He leaned one shoulder against the concrete wall, looking down at her trembling form. "Don't you think that was a bit cruel?"
I wonder how loud her heart is right now.
Yoru didn't lift her head. Her response came muffled against her knees, soaked in venom.
"Scum."
"Mm." Riku didn't sound offended. He sounded entertained. "Stand up."
Because you can't. And we both know it.
A beat of silence. Then Yoru's hands pressed flat against the dusty concrete and she pushed herself upward, thighs trembling, calves shaking, the hem of her skirt whispering against her skin as she rose unsteadily. Her back found the wall. She made it almost to full height—
Riku's thumb pressed the small wireless remote in his pocket to the sixth setting.
The effect was instantaneous. Yoru's knees buckled like someone had cut her strings. A strangled sound tore from her throat—not quite a moan, not quite a gasp, something animal and involuntary—and her body folded forward. Riku caught her by the waist before she hit the ground, one arm hooking around her midsection, pulling her upright against him. Through his palm he could feel the vibration transferring faintly from deep inside her, buzzing against his forearm where it pressed her lower belly.
The scent hit him. Jasmine shampoo layered over something sharper, warmer—salt and arousal, that unmistakable musk that clung to overheated skin. Mixed with the concrete dust it became something almost narcotic.
"If you can't stay on your feet," Riku murmured against the shell of her ear, breath ghosting across the fine hairs at her temple, "I'm going to have to add interest."
Yoru's face—invisible in the darkness but burning hot enough that Riku could feel the radiant heat when he leaned close—turned sharply away.
"Wh-what interest—"
"You know exactly what I mean."
She tried to stand on her own. Pushed against his chest with both palms, attempted to lock her knees. The vibrator hummed mercilessly inside her, buzzing at a frequency that turned her thigh muscles to water. Her legs wouldn't stop shaking. Every attempt to straighten them sent a fresh wave of sensation rolling up through her pelvis and she'd buckle again, hips jerking, fingernails scraping against the front of Riku's shirt.
"Nnh—aahh… hahh…"
This is wrong. This is wrong this is wrong Shirou is right outside the door and I—
Her body slid downward. Riku caught her again—this time deliberately, hooking both hands under her thighs and pinning her back against the cold concrete wall. Her shoulder blades pressed into the rough surface. The chill of the wall through her thin cardigan contrasted violently with the inferno burning between her legs, and the dissonance made her gasp.
Riku's left knee pushed between her thighs, separating them slowly, firmly, until her weight settled partially on his leg. Through his jeans he could feel wet heat soaking into the denim. Her inner thighs were slick.
"You… what are you—"
She already knows.
He leaned in. Close enough that his lips nearly grazed her cheek. His breath was warm, steady, maddeningly calm against her flushed skin.
"Ready for the interest payment?"
"Don't—" Yoru shook her head rapidly, dark hair whipping across her face. "Sto—the thing is still—it's still inside—"
Riku's right hand slid down the outside of her left thigh, fingertips tracing the goosebumped skin beneath the hem of her skirt, curling inward along the sensitive crease where thigh met hip. He lifted her leg, hooking it over his hip. The position spread her open further and the vibration intensified against her g-spot at the new angle, and she keened—a high, thin sound like a violin string about to snap.
"Please—nnhh—the thing, it's still in me—!"
Her voice broke on the last word. Desperate. Trembling.
Riku leaned to her ear. "Before Shirou came in. I tossed it to you. You put it back in yourself, remember?"
That was the deal. She inserts it, I hide. I insert it, I stay. She chose to do it herself. Chose with her own trembling fingers, shoving the slick little vibrator back inside her cunt while Shirou's footsteps echoed above us. She made that choice. And her body made another one entirely.
"Take it out yourself, then."
Silence.
Yoru's breath came in shallow, hitching gasps. Her right hand released its death-grip on Riku's shoulder and traveled downward, shaking, past her bunched-up skirt, between her spread thighs. Her fingers found the small silicone cord and pulled, slowly—
"Mmph—aahhn~!"
The vibrator slid free with a soft, obscene schlck, trailing a thin string of clear fluid that caught no light in the absolute darkness but that Riku could hear, could feel drip warm against his wrist. The toy buzzed angrily in Yoru's palm, still on the sixth setting, wet and hot from her body.
Before she could exhale—
Riku's hands locked under both her thighs and lifted. Her back scraped up the concrete wall, cardigan riding up, bare skin dragging against rough stone. Her legs hooked instinctively around his waist as the ground vanished beneath her, and both her arms flew to his neck, fingers lacing behind his nape, clinging. The vibrator tumbled from her grip and clattered down two steps before going still.
He freed himself with one hand. She felt the blunt, thick head of his cock press against her entrance—scalding, impossibly hard, the ridge of him nudging through folds that were swollen and drenched and twitching with residual vibration. No barrier. No hesitation.
He pushed in.
"NNGH—aah, ahh, ahhh~!"
Yoru's head snapped back against the wall. Stars burst across her vision—or maybe that was just the absolute darkness playing tricks, the total sensory deprivation making every physical sensation louder. He was thick enough that the stretch burned even through how wet she was, the fat shaft of his cock spreading her open inch by deliberate inch until his hips pressed flush against hers and she could feel his pulse inside her, every vein and ridge of him pressed against her clenching walls.
No no no no—
「Shameless Thief」activated.
The ability pulsed through her like a second heartbeat. Yoru's rational mind—the part screaming that Shirou was sitting twenty feet away on the other side of a fire door—drowned beneath a warm, syrupy tide that softened every sharp edge of her resistance into something pliant and hungry.
Her hips moved.
Not by conscious choice. Her body rolled against him, grinding down onto his cock, inner walls squeezing rhythmically around his girth in a way that made Riku grunt low against her collarbone. Her thighs tightened around his waist. Her heels dug into the small of his back, pulling him deeper, and she could feel the tip of him pressing against her cervix, a dull sweet ache that pulsed in time with the ability's influence.
"Hahh… hahh… nn—fuhh—"
I hate him. I hate this. I hate that it feels—
Her thought dissolved.
Riku fucked her in slow, grinding thrusts that pinned her to the wall with each forward snap of his hips. The concrete scraped her shoulders raw through the thin cardigan. Each stroke dragged the full length of him out until only the swollen head remained, stretching her entrance, before driving back in with a wet, meaty slap that echoed in the dead stairwell like a secret being told to no one.
His right hand gripped her left thigh hard enough to bruise—five distinct points of pressure that would bloom purple by morning. His left arm supported her weight beneath her ass, fingers digging into the soft flesh there, spreading her wider with each thrust so he could push deeper, the angle sending the head of his cock dragging across that spongy spot inside her that made her vision white out.
"Ahhn—ahh~! Hahh—mm, mmmph—!"
She bit down on his shoulder to muffle herself. Tasted cotton and salt and the clean, woody scent of his cologne—sandalwood and cedar—mixing with the raw musk of sex that was thickening in the stairwell air like fog. Her teeth left crescent marks through his shirt.
Shirou's right outside. Shirou is sitting on the floor right outside and I'm—
Riku tilted his hips and thrust up, and her thought shattered into static.
"Nnh—ah, AH—fuahh~!"
Her orgasm hit without warning—a full-body seizure that locked her thighs around his waist and arched her spine off the wall, mouth open in a silent scream, walls clamping down on his cock in rapid, fluttering contractions. Riku felt her come undone around him—felt the gush of wet heat flood over his shaft and drip from where they were joined, soaking into his jeans at the waistband. He didn't stop. His rhythm only shifted—shorter, harder strokes that punched the air from her lungs and kept the orgasm rolling, cresting, cresting, refusing to end.
"Too—too much—hahhn—nnh, nnhh~!"
She was sobbing. Tears and sweat tracked down her flushed cheeks, and her fingers clawed at his shoulders, at his hair, unable to decide between pulling him closer and pushing him away. The overstimulation burned like electricity through nerves already wrung raw by forty minutes of vibrator torment, and her body couldn't process the input anymore—pleasure and pain blurring into a single white-hot frequency that made her toes curl so hard they cramped.
Riku came with a low groan muffled against the curve of her neck, hips slamming flush one final time, cock twitching deep inside her as thick, hot ropes of cum flooded her clenching walls. She felt each pulse—one, two, three, four—felt the warmth spread and fill her until it had nowhere to go, until she could feel it leaking around his shaft, sliding down the cleft of her ass, dripping onto concrete in the dark.
Oh god. Oh god, he came inside.
He held her there, pinned to the wall, both of them breathing hard. The stairwell reeked of sex—sharp and sweet and unmistakable, cum and arousal and sweat layered over concrete dust. Somewhere below, the dropped vibrator buzzed its last gasp of battery life against a step and went silent.
Riku lowered her gently. Her legs barely held. She gripped the handrail with white-knuckled fingers and stared at nothing, chest heaving, skirt askew, thighs trembling and slick with fluids she couldn't distinguish anymore.
I need to clean up. I need to—Shirou is waiting. Shirou is waiting right outside.
What have I done?
---
[7th Floor Corridor, Outside Apartment 7-B — 10:24 PM]
"Shirou, let's go back inside."
Thirty minutes. It had taken her thirty minutes to piece herself back together in the dark—wiping what she could with the inside of her cardigan, smoothing her skirt, finger-combing her hair, pressing cold palms against her burning cheeks until the flush retreated to something that could be explained by crying. She'd cried too, genuinely, though the tears had more to do with confused shame than anything Shirou had said. Her legs still felt like they belonged to someone else.
Shirou scrambled to his feet so fast he nearly tripped over his own shoes. His face was blotchy, eyes red-rimmed—he'd been sitting there the entire time, and from the state of his hair, he'd nearly torn patches of it out.
She's talking to me. She came back. She doesn't hate me.
"Yeah. Yeah, of course."
I'll make this up to her. I swear I'll make this right.
Footsteps on the stairwell door's far side—and then Riku emerged from the first-floor entrance at the end of the corridor, hands in his pockets, expression pleasantly neutral, not a hair out of place. He'd taken the long way around. Down seven flights and back up the elevator, probably. Cool as tap water.
Yoru's gaze flickered to him. Almost involuntary.
Her thighs pressed together, tighter. Beneath her skirt, a thick bead of white slid from between her swollen folds, tracing a slow, warm line down her inner thigh, catching in the fine hairs just above her knee before soaking into the top of her thigh-high sock. She didn't dare shift her weight.
Don't move. Don't move. It'll drip onto the floor.
Shirou turned to face Riku. Drew himself up. And then folded at the waist in a precise ninety-degree bow, forehead aimed at the floor.
"I'm sorry! My behavior earlier was completely out of line. Please forgive me!"
I swallowed my pride for Yoru. Because she matters more than my ego. Because I'm going to be better than what I was an hour ago.
Riku watched the top of Shirou's bowed head with an expression that could have been mistaken for graciousness.
"Don't worry about it." His gaze drifted, just for a heartbeat, to the hem of Yoru's skirt. "Yoru already made it up to me."
And then some.
Shirou straightened, blinking. "Made it up to you?"
He turned to Yoru, brow furrowed.
She felt the question hit her like ice water. Her tongue went thick in her mouth. A fresh trail of warmth oozed past her entrance and she locked her knees together so hard her calves ached.
"It's—it's nothing. I just explained to Riku about our… about our situation. About you and me. So he understands that what happened earlier, you know, it came from a real place."
Please don't ask more. Please please please—
Riku stepped smoothly into the gap. "She told me how deep your bond goes, and honestly, I feel like I was the one overstepping. My bad, Shirou." He dipped his head with precisely calibrated humility.
The tension drained from Shirou's shoulders. A shaky, grateful smile broke across his face.
See? I was overthinking it. Yoru just talked to him. Explained things. That's all. Compensation meant—she smoothed things over.
What else would it mean?
God, I'm disgusting for even letting the thought cross my mind.
Shirou reached up and rubbed the back of his neck, exhaling hard through his nose, and fell into step beside Yoru as the three of them walked back toward the warm light spilling from apartment 7-B's open door. Yoru's hand found Shirou's sleeve—just the fabric, not his skin—and held on loosely, her gaze fixed straight ahead, her steps small and careful and deliberately even, every muscle below her waist clenched tight against the slow, damning trickle that wouldn't stop.