The digital clock on Kimiko's nightstand read 4:47 AM. She knew because she'd watched every minute change for the last six hours.
Her body ached from lying in the same position, curled on her side facing away from the door. The taste of chamomile tea still lingered on her tongue, bitter and cold. Yukio had left the cup outside her door hours ago. She'd heard his bare feet on the creaky floorboards, the soft clink of ceramic against wood, then silence.
The kiss replayed in her mind on an endless loop. The warmth of his hands on her thighs. The shock in his violet eyes. The way he'd stood there, frozen, as she fled like a coward.
What have I done?
Kimiko rolled onto her back and stared at the ceiling. Sleep wouldn't come. Every time she closed her eyes, she saw Yukio's face. Not the confident mask he wore for the world, but the vulnerable expression he'd shown her in those few seconds before she ran.
She needed something to anchor herself. Something to remind her of who they were supposed to be.
Kimiko slipped out of bed and padded to her closet. Her fingers found the familiar wooden box hidden behind her winter coats. The weight of it felt heavier than usual as she carried it back to her futon.
The box opened with a soft creak. Photo albums, certificates, old school reports. The fragments of their family history. She pulled out the thick album from the bottom and settled it in her lap.
The first page showed Yukio at age five, gap-toothed and grinning as he held up a sandcastle. Kimiko remembered taking that photo at the beach. She'd been thirteen, already tall enough to need to crouch down to get the right angle.
She flipped through more pages. Yukio's first day of elementary school, swimming in his oversized uniform. His middle school graduation, where he'd won an award for academic excellence. Normal moments. Happy moments. The kind of memories that made them feel like a real family.
But her fingers kept moving backward, past the comfortable lies, until she reached the very first page.
There should have been a hospital photo here. A newborn Yukio in their mother's arms, red-faced and wrinkled like all babies. Instead, there was a single faded Polaroid taped to the page.
A wicker basket sat on their apartment doorstep. Inside, wrapped in a soft blue blanket, was a tiny baby with black hair. His eyes were closed, one small fist pressed against his cheek.
Kimiko's hands shook as she peeled back the photo's corner. Underneath, folded and yellowed with age, was a piece of paper no bigger than her palm.
She'd found it years ago, tucked inside one of their mother's books after the funeral. The handwriting was elegant but frantic, as if written in desperate haste.
His name is Yukio. Please, keep him safe. Raise him as your own. He must never know what he is. Don't let him find him.
The word "him" was underlined twice, black ink slashing across the paper like a wound.
Kimiko had been seventeen when she discovered the note. Old enough to understand what it meant. Young enough to convince herself it didn't matter.
Their parents had told her Yukio was a gift. A miracle baby who'd appeared when they'd given up hope of having another child. She'd believed it because she wanted to. Because the alternative was too complicated to face.
But now, sitting in the pre-dawn darkness with the taste of his lips still on hers, the truth was impossible to resist.
He's not my brother.
The thought should have brought relief. Instead, it brought terror.
Because if Yukio wasn't her brother, then the kiss wasn't the worst thing she'd ever done. It was the most honest thing that had ever happened between them.
And that scared her more than anything.
Kimiko pressed the note against her chest and tried to breathe. Her parents had raised Yukio as their own son. She'd played the role of big sister for thirteen years. It wasn't a lie anymore; it was who they were.
The kiss changed everything because it made her admit what she'd been hiding from herself. The way her heart raced when he smiled at her. The jealousy that twisted in her stomach when other girls looked at him. The reason she worked herself to exhaustion to give him everything he needed.
It wasn't sisterly love. It had never been sisterly love.
Kimiko folded the note and slipped it back under the photo. Her reflection stared back at her from the album's plastic cover, distorted and strange in the dim light.
I could tell him.
He deserved to know the truth about who he was. Especially now, heading to U.A., stepping onto a stage where the whole world would be watching.
What if "he" was still out there? What if knowing made Yuki search for answers?
But the selfish part of her, the part that had kissed him and wanted to do it again, knew the real reason she was considering confession.
If she told him now, right after what happened in the kitchen, what would he think? That she was using the truth to justify her feelings? That she'd manipulated him when he was vulnerable and happy about U.A.?
He would hate her. And worse, he would leave.
The sister lie was the only thing keeping him tethered to her. It guaranteed her a place in his life forever. If she cut that rope, what would be left?
Kimiko closed the album and hugged it to her chest. Outside, the city was starting to wake up. She could hear the distant rumble of early morning trains, the soft hiss of tires on wet pavement.
In a few weeks, Yukio would be gone. Not forever, but to U.A.'s campus for orientation and dorm assignments. Soon he'd be living in Alliance Heights, surrounded by other hero students. Smart, beautiful, talented girls who would see him as she did.
The thought made her stomach clench.
Those girls wouldn't just be competition for his attention. They'd be a threat to everything she'd built. If Yukio formed deep bonds with someone else, he might start asking questions she couldn't answer. He might realize that the life they'd shared was built on a foundation of lies.
Kimiko stood and returned the box to its hiding place. She could hear Yukio's steady breathing from the living room, finally asleep on the couch.
She wanted to go to him. To curl up beside him and pretend the kiss had never happened. To go back to being the supportive sister who believed in his dreams.
But she couldn't. Not yet. Because now she knew the truth about herself, and that knowledge changed everything.
The kiss wasn't wrong because they were siblings. The kiss was dangerous because it threatened her control.
She couldn't lose him. Not to U.A., not to other girls, not to the truth about his past. To keep him safe, and more importantly, to keep him hers, the lie had to continue.
Kimiko pressed her forehead against the cool glass of her bedroom window. The sun was starting to rise, painting the sky in soft shades of pink and gold. Soon, Yukio would wake up and they'd have to face each other.
She would put on the mask of the loving, supportive sister. She would make him breakfast and smile and tell him how proud she was.
It wouldn't be just a performance anymore. It would be an act of survival.
Because losing him, watching him walk away from everything they'd built together was unthinkable.
Kimiko took a deep breath and straightened her shoulders. She had work to do. A role to play. A secret to keep.
The sister lie would hold. It had to.
Even if it killed her.