The man next door

Aiko lay on her back with her eyes open, staring at the dark ceiling like it could answer her. The apartment was quiet in the safe way—fridge hum, distant train, the soft moving sound of Haruto turning in his sleep. Then the wall started again. Not loud, not clear, just enough. A rhythm from next door. A breath that didn’t belong to her.

She pressed her pillow over her ear. It didn’t help. The sound slipped through anyway, flat and close, like someone had leaned their mouth against the plaster. Her cheeks heated. Shame came first, sharp and fast, as if she had done something wrong by listening.

Haruto slept beside her, calm and perfect. He always was. He never woke up angry. He never raised his voice. He checked the lock twice before bed, like that was love. Aiko had married her life to that kind of safety. She told herself she didn’t notice the neighbor. She told herself the noise was just pipes or music.

But her body didn’t agree with her lies. Even when she didn’t want to think about it, the sound made her stomach twist. Her thoughts turned mean, like a warning sign. _This is humiliation. This is not for me._ She rolled onto her side, facing the wall, and counted breaths until her heart slowed.

The neighbor’s bedroom kept moving. Then—silence. Aiko waited for the next wave, waiting like a person who couldn’t change the outcome. When nothing came, she felt ridiculous, like she had been standing in front of a closed door. She pulled the blanket higher and tried to sleep again.

She finally gave up and sat up. Her room smelled like laundry soap and night air. Her phone glowed on the bedside table. 2:17 a.m. The numbers looked too bright, like they were judging her for being awake. She turned her head toward the wall, listening one more time.

Footsteps. Not in her own hallway. Next door. Then a door handle clicked, careful and slow. Aiko held her breath. The smell of smoke and something metallic drifted through the thin space under the wall. It wasn’t strong, but it was wrong for a normal apartment.

A soft knock hit her bedroom door. Not loud. Not casual. Confident. One knock. A pause. Then another, like the person knew she would answer even if she didn’t want to. Her pulse jumped, fast and stupid. She slid out of bed, careful not to wake Haruto.

Aiko opened the door a crack. The hallway light made everything look flat. Her neighbor stood there in dark clothes, tattooed forearms resting near his sides. Renji Saitō. He had moved in a month ago, and ever since, he made the building feel like it had a secret second life.

He smiled, but his eyes didn’t soften. “Aiko,” he said, like he was greeting her at a café. Her name in his mouth made her throat tighten. She hadn’t told anyone he lived next door. She hadn’t told anyone she heard him.

“It’s late,” Aiko managed. She kept her voice low. She didn’t want Haruto to hear. “What do you want?” The question came out harsher than she meant. Her chest rose and fell too fast.

Renji tilted his head. “Late for sleep,” he agreed. He looked past her, into the room behind her, as if he could see Haruto even in the dark. “I didn’t mean to bother you. But the wall is… thin.”

Aiko tried to close the door, but he put one hand on the frame. Not pushing hard. Just enough to stop her. His touch was warm through the air, and it made her skin crawl. “You work in the morning,” he said. “You drink coffee at exactly seven twenty. You don’t use sugar.”

Her stomach dropped. She had never mentioned sugar to him. She didn’t even talk to him. She checked her messages, her schedule, her life. She didn’t share it. “How do you—” she started.

Renji’s smile sharpened. “Relax,” he said. “I’m not here to scare you.” The way he said _relax_ felt like a command wrapped in a friendly tone. “I heard you move. You turned the pillow. Twice.”

Aiko felt heat rise again, but this time it wasn’t just shame. It was anger. She hated that he knew. She hated that her body had given him anything to notice. “Stop listening,” she said, and surprised herself with the bluntness.

Renji leaned closer, not enough to touch her, but close enough that she could smell smoke and rain on his jacket. “I don’t have to listen,” he said softly. “I live next door. I can hear everything. I just didn’t think it would bother you.”

Safe. The word hit her like a joke. In her mind, Haruto was safe. Haruto was the man who fixed the broken hinge. Haruto was the man who folded her socks the right way and asked if she ate enough. Haruto was a quiet promise. Aiko glanced back toward her bedroom, where his shape lay under the blanket.

Renji watched her glance. “Your boyfriend is asleep,” he said. “He won’t wake up.” His voice stayed calm, but the confidence made Aiko’s skin tighten. It was like he had already decided what rules she was allowed to follow.

Aiko swallowed. Her tongue felt too thick. “Why are you here?” she asked again, because if she kept asking questions, maybe she could keep control of her fear. Renji looked at her like she was a problem he enjoyed solving.

Renji stepped back half a pace, like he was giving her room to breathe. “I want to talk,” he said. “Not here. Not long.” Then his eyes flicked to her doorframe, to the small gap where light from the hallway painted her floor. “Tomorrow. Ten minutes after you leave.”

Aiko’s mouth went dry. She didn’t go anywhere without Haruto’s calm approval. She didn’t do secret meetings. She didn’t even like surprises. “No,” she said, and her voice shook on the last word.

Renji didn’t argue. He only looked pleased, like refusal was part of the game he planned to win. “Then at least be smart,” he said. “If you hear it again and you can’t sleep, don’t pretend it’s nothing. It’s better to know.”

Aiko stared at him. Under the hallway light, his tattoos looked darker than they had in the day. His jacket still held the faint smell of smoke, like the smell had roots. “Who are you?” she asked. “Really.”

Renji’s smile faded. For a second, his face looked tired, not playful. “A neighbor,” he said. Then he added, almost gently, “And you should lock your door tonight. Properly.”

He reached into his pocket and pulled out a small paper slip. He didn’t hand it to her. He pressed it against the inside of her doorframe with two fingers, like he was leaving a mark. On the paper was a phone number written in neat ink. No name. No explanation.

Aiko didn’t move. Her hand hovered near the paper but didn’t touch it. She could feel her heartbeat in her fingertips. Renji stepped away, and the hallway seemed colder without him in it.

Before he turned, he spoke one last time. “Haruto doesn’t hear the wall,” he said. “But you do.” His eyes met hers. “So you’re the one who will decide what happens next.”