Chapter 1: The Shirt on Her Skin
The key stuck in the deadbolt, the metal scraping a sound that set Mizuki’s teeth on edge even before she shouldered the door open. The smell hit her first—burnt rubber, motor oil, and underneath it, the sweet, cloying scent of cherry blossom body spray. It was always like walking into a garage that someone had tried to perfume.
“Hello? Sukuna? I brought the takeout you wanted,” she called out, her voice too bright, too cheerful against the dim, chaotic gloom of the apartment.
The living room was a monument to disassembly. A carburetor sat gleaming dully on the coffee table, surrounded by a nest of greasy rags. Against the far wall, the skeleton of a motorcycle engine leaned precariously, casting long, jagged shadows in the late afternoon light bleeding through the dusty blinds.
Her eyes found them on the couch.
Sukuna was slouched deep into the cushions, one tattooed arm thrown along the back. And curled into his side, tucked under that arm like she belonged there, was a girl Mizuki had never seen. She had to be Megumi. Long, blue-black hair fanned over Sukuna’s chest, and she was wearing what was unmistakably his shirt—a faded black band tee, swimming on her petite frame. It was so large the neckline slipped off one pale shoulder. She wasn’t wearing anything else. The thin, worn cotton did nothing to conceal the shape of her body underneath, the peaks of her nipples pressed against the fabric, outlined clearly as she shifted.
Mizuki’s grip tightened on the plastic bag of food. Her knuckles went white.
“Took you fucking long enough,” Sukuna said, not looking at her. His red eyes were fixed on the top of Megumi’s head. His voice was its usual gravel, but there was a laziness to it, a warmth she rarely got. “Was the place besieged by idiots or did you just forget how to walk?”
“Traffic,” Mizuki managed, the word dry in her throat. She stood frozen in the entryway, a visitor in her boyfriend’s home.
Meguni stirred then, turning her face into Sukuna’s neck and nuzzling there. She made a soft, sighing sound. “Kuna-nii, you’re warm.” Her voice was a low, content murmur, meant only for him.
“Course I am, princess. You stole all the blankets again.” He didn’t push her away. His fingers, stained with permanent grease, came up and carded slowly through her dark hair. A gesture of such effortless tenderness it felt like a physical blow to Mizuki’s sternum.
This was his sister. The one he said was shy. The one he said needed looking after.
Megumi finally deigned to notice her. She lifted her head, those large, dark eyes blinking slowly, languidly, like a cat emerging from a sunbeam. There was no surprise in them, only a cool, assessing interest. She didn’t sit up, didn’t adjust the shirt. If anything, she pressed herself more firmly against Sukuna’s side.
“You must be Mizuki,” Megumi said. Her smile was small, polite, and utterly empty. “I’ve heard so little about you.”
Sukuna snorted. “Be nice, Megs. She carries the food.”
“I’m always nice, nii-chan.” Megumi’s gaze swept over Mizuki, from her sensible flats to her knee-length skirt and cashmere sweater. The teacher’s outfit. A look of faint amusement played on her lips. “It’s so sweet of you to bring dinner. Kuna-nii usually just feeds me leftovers from his shop.”
The possessiveness was casual, absolute. He feeds me. He clothes me. I am his.
“It’s… nice to finally meet you, Megumi,” Mizuki forced out, walking on stiff legs to set the bags on the cleared corner of the coffee table. The air between them felt thick, charged with something she couldn’t name. “Sukuna talks about you all the time.”
“Does he?” Megumi’s eyebrows lifted slightly. She tilted her head back to look at Sukuna, her nose brushing his jaw. “What do you say about me, Kuna-nii? All good things, I hope.”
“I say you’re a pain in my ass who eats all my goddamn rice,” he said, but he was grinning, a sharp, fond thing that carved lines around his eyes. He squeezed her shoulder. “And you are. But you’re my pain in the ass.”
“Yours,” Megumi echoed, the word a soft, satisfied purr. Her hand came up, fingers splaying flat over the tribal ink on his chest. A claim.
Mizuki busied herself with unpacking the containers, the clatter of plastic lids suddenly obscenely loud. Her face felt hot. This was wrong. This was so, so wrong. But what was she supposed to say? Your sister is practically sitting in your lap in your shirt and you’re petting her like a lover. She was the outsider here. The interloper. The thought was a sick, sinking weight in her gut.
“So, Megumi,” Mizuki began, desperate for some thread of normalcy. “Sukuna said you’re thinking about college? That’s exciting. Any idea what you want to study?”
Megumi let out a light, airy laugh, the sound tinged with condescension. “Oh, no. I could never leave Kuna-nii alone in this pigsty. He’d starve. Or blow the place up trying to microwave ramen.” She looked up at him, her expression softening into something Mizuki had never seen on Sukuna’s face—open, unguarded adoration. “Someone has to take care of him.”
“The fuck I need taking care of,” Sukuna grumbled, but he didn’t disagree. He just rested his chin on the top of her head, his gaze drifting over to Mizuki. It sharpened, turning assessing. “You gonna just stand there judging the décor, or are you gonna sit the hell down? You’re blocking my view of the shitty TV.”
There was nowhere to sit. The only other chair was buried under a pile of leathers and engine parts. Mizuki hovered, perching awkwardly on the very edge of the armchair she had to clear first.
The next twenty minutes passed in a strange, slow-motion torture. Megumi finally uncurled herself to eat, but she did it without leaving the couch, her bare legs tucked beneath her. She reached across Sukuna for the soy sauce, her chest brushing his arm. She fed him a piece of her ginger from her chopsticks, her fingers lingering near his mouth. He took it without comment, without even looking, as if this was their most mundane routine.
He called her ‘princess’. He called her ‘good girl’ when she passed him a beer. The terms of endearment he’d never once used with Mizuki dripped from his lips like honey, each one a tiny, precise cut.
His insults, meanwhile, were reserved for Mizuki. “You eating or playing with it? Christ, no wonder you’re so thin, you eat like a bird shits.” Or, when she asked about his work, “Why? You writing a fucking thesis? It’s work. I fix broken shit for morons who break it again. Happy?”
Megumi would watch these exchanges with that same faint, knowing smile, sipping her soda. Once, when Mizuki flinched at a particularly crude remark about the school where she taught, Megumi caught her eye. She didn’t smirk. She just watched, her dark gaze cool and impenetrable, and gave the smallest, most imperceptible shrug. This is how it is. This is him with you.
The final blow came as Mizuki was gathering the empty containers, her hands trembling with a quiet, building fury and despair. She needed to use the bathroom. The hallway was dark, the door to Sukuna’s bedroom ajar. Pushing it open, she fumbled for the light switch.
The room was as messy as the living room, but that’s not what stopped her breath. It was the bed. A tangle of black sheets, clearly slept in by two. And on the floor, near Sukuna’s side, was a small, lace-trimmed camisole. Pale blue. It wasn’t hers.
A sound from the doorway made her jump. Megumi was leaning against the frame, having followed her silently. She’d put on a pair of shorts, but she was still in Sukuna’s shirt. She looked at the bed, then at Mizuki’s horrified face.
“Oh,” Megumi said, her voice a soft, innocent whisper. She padded into the room, bent down, and picked up the camisole, folding it neatly. “Sometimes I get nightmares. The couch is too far from nii-chan.” She met Mizuki’s eyes, and this time, the innocence was gone, stripped away to reveal something cold and calculating beneath. “He doesn’t like me to be scared. He always lets me stay.”
She held Mizuki’s gaze for a long, paralyzing moment, then brushed past her, returning to the living room. Mizuki heard her voice, sweet and light. “Kuna-nii, are you done with your beer? I’m getting cold again.”
Mizuki stood in the dark bedroom, the smell of Sukuna’s cologne and Megumi’s cherry blossom spray merging into one nauseating perfume. The truth, ugly and undeniable, settled into her bones. She wasn’t just dating a man with a close sister. She was a guest in a house with no room for her, a temporary fixture in a world built for two. The love she’d carefully nurtured for six months curdled in her chest, replaced by a chilling, certain dread.
From the living room, Sukuna’s laugh grated through the air, low and real. It was answered by Megumi’s giggle, a seamless, private harmony. Mizuki finally found the switch, flooding the room with a harsh, unforgiving light. It didn’t help. The shadows felt deeper now, etched into the very walls.