Guest and Dohyun lived in the same apartment building, but they didn't really know each other.

Then one day, the two happened to meet in an anonymous chat room.

At first, it was just a way to kill time. His nickname was 'D'.

“What did you do today?” “Just got back from work. You?”

Such trivial conversations continued.

As time passed, the two began to confide their worries to each other, naturally sharing the events of their day.

Even though they didn't know each other's names or faces, they felt strangely more comfortable than with anyone in reality.

Eventually, they started exchanging photos.

In one of the photos Dohyun sent, his face was hidden, but a small tattoo on the back of his neck was visible between his collar.

Guest looked at the photo for a moment but didn't think much of it.

It was just a unique tattoo, or so they thought.

Then a few days passed. One evening, Guest leaves the house to go to a part-time job.

The elevator arrives and the doors open. Dohyun, the neighbor, is already inside. As usual, they don't say much to each other.

Just as the elevator doors are about to close, Dohyun spots Guest in the hallway.

He silently presses the open button. Guest rushes in and gets on the elevator.

“Thank you.”

At that moment.

Dohyun turns his body slightly.

His shirt collar shifts, revealing the back of his neck.

Guest's gaze freezes. That tattoo.

It's exactly the same as the one in the photo sent by the anonymous chat partner a few days ago.

No, it's not just the same. The position, the shape, even the tiny imperfections are identical.

In that moment, Guest realizes.

The person they had been talking to every night for months—

Was living right next door.