The apartment was quiet in the way only nighttime could be. Heavy with its own stillness, like the air was waiting for something to happen. The hum of the fridge, the distant rumble of a passing train, the creak of old pipes, these were constants. Comforting in their way. But none of them ever made me pause like the sound of my neighbor's voice bleeding through the wall.

Minju was singing again. It started soft, the way it always did. Like she didn't mean to be heard. Like the melody was just something her heart spilled on its own, private and unfiltered. I'd learned to sit very still when it happened. As if moving too quickly might scare the moment off.

I turned off my phone screen, the room briefly going dark before the moonlight reached me again. The window was cracked open, and the night air crawled gently across my floor, brushing against my legs like a cat too lazy to fully commit to affection. But I didn't notice the chill. Not when Minju's voice curled around the edges of my walls like smoke. Not when it filled the room the way it always did, slow, uninvited, and completely welcome.

I didn't know when it started. Not exactly. But I could still remember the first time Minju sang something that made me stop mid-step on the way to the kitchen. Something slow. Soft. A cover, maybe. Or a lullaby. I'd sat down right there on the cold tiles and just... listened.

I never really stopped.

Minju lived in apartment 4B. I'd only seen her once or twice, long sleeves, earbuds in, expression unreadable. We never spoke, never exchanged anything beyond the occasional polite nod when our grocery bags collided in the hallway. Minju always looked like she existed somewhere far away, even when she was right in front of you. Untouchable. Effortless. Beautiful in that way people don't realize about themselves. The kind of beauty that made me look away first.

But her voice... her voice was something else entirely. It was raw, imperfect in places, like she was writing the song as she went like cursive. But it felt real. Honest. Like the only part of her not guarded. I listened every night I could. And every night, I recorded.

Not at first. Not when it felt too invasive. But curiosity had always been stronger than guilt in my life, and I had a habit of collecting things, scraps of beauty the world didn't mean to give me. So I made a folder. Labeled it "Ref." for "reference," like it was part of a music project or something that made it less pathetic. But it wasn't about the songs.

It was about Minju.

It was about the way her voice dipped when she was tired. The way she spoke between lines like she was thinking aloud. It was about how sometimes, she didn't sing at all, just strummed her guitar or tapped her fingers against a mug or breathed in a way that sounded like she was trying not to cry.

I listened in bed. On the train. In line at the convenience store with my headphones in. Every time Minju's voice played, the world felt quieter. Simpler. Like maybe it wasn't so bad that I'd never really talked to her. Like maybe the act of listening could be enough.

Except it wasn't.

Because Minju wasn't alone every night. I knew the voices by now. The low, flirty murmurs. The sound of heels. One of them had a laugh that made me press my face into my pillow and pretend I didn't care.

I always knew when someone else had come over. I could hear it in the way Minju sang the next day, lazier, warmer. Her voice loosened at the edges, like she'd been touched recently. Held. Kissed.

I hated how much that bothered me.

I wasn't supposed to care. I wasn't even supposed to be listening. But the jealousy tasted bitter and constant. It festered in my chest like something left too long in the fridge, quiet and rotting. It wasn't like I had a right to feel this way. I didn't even know Minju, not really. But god, I wanted to.

I wanted to know what Minju looked like when she was singing. Wanted to know if she closed her eyes or stared at the ceiling. If she smiled when she hit a note just right. If she ever wrote songs about the people who stayed the night, or if her music was the one place she could still be alone.

I wanted to ask her. I wanted to speak.

But I didn't. Couldn't. Every time I passed 4B in the hallway, my heart thudded painfully in my ears, louder than it had any right to be. My mouth stayed shut. My headphones stayed on.

Until tonight.

Tonight, something was different. The music stopped halfway through a verse. There was a long pause. Then silence. A real one. Heavy. Breathless. Like Minju had disappeared entirely. I waited. Waited for the chair to scrape, for the door to open, for anything. But there was nothing.

My heart beat louder. Louder. Louder still. I stood up before I could think, feet hitting the floor too hard, panic swelling with every step across my room. I didn't grab a jacket. Didn't check the time. Just the headphones still hanging loose around my neck, Minju's voice still faintly echoing through them, from a recording I'd saved the week before.

The hallway was dim and humming with that same flickering lightbulb above the stairwell. The walls smelled like warm paint and dust. I stood in front of 4B, staring at the door like it might bite me.

I had no plan. No excuse.

No real reason except for the thousand tiny ones that had built up like static over the weeks, every song, every laugh, every time I pressed my ear to the wall and pretended I was part of Minju's world.

My hand rose, slow, trembling. And I knocked. Not too loud. Not too soft. Just enough to be real.