The Roster Hidden in Locker B-18

Before the first train arrived, the station looked like night and morning had been laid over each other.

Ji-an had almost run all the way from the public phone booth beneath the Dongmun overpass. The sky was still dark, but the platform boards were already preparing for the first departures. It was not her first sleepless night since the funeral, yet this dawn carried a different kind of fatigue. Not sleepiness—something in her body was braced against danger and refused to let go.

The booth had left her with more than Su-bin's voice.

When Ji-an had gone to hang up the receiver, the back of her hand scraped the metal coin return. A slip of paper had caught on an unclosed seam inside. A crumpled receipt fragment and a small rusted key. She had shoved both into her pocket without thinking. Now, sitting on a bench at the edge of the concourse, she unfolded the receipt.

Dongmun Station Locker B-18.

The usage time was 11:24 p.m. on the night before Su-bin died.

Ji-an tightened her hand around the paper. Su-bin had truly been leaving things in stages. First the phone booth, then a station locker. As if she had calculated exactly when her sister would have enough space after the funeral to move alone.

People waiting for the first train drifted gradually into the hall. Someone coming off a night shift. An old man in training clothes. A student with earbuds in. In the middle of all that ordinary movement, Ji-an felt as if she alone were standing in a different time.

Locker B-18 sat at the far end of the underground passage. The sticker marking its number had peeled halfway off, and long scratches crossed its surface. Ji-an inserted the rusted key and turned it. The hard scrape of metal echoed down the passage.

Inside was a black cloth bag.

She could not reach for it right away. Whatever was inside had been placed there by Su-bin herself, at the edge of her life. That fact terrified Ji-an in a way she had not expected.

The contents looked almost ordinary at first. An old backup phone. A charging cable. A paper map of the Dongmun area. A waterproof file. And one folded memo.

Rooftop greenhouse, Serim Villa 301.

Su-bin's handwriting. Slightly rising at the end because she had written fast. Ji-an would have known it anywhere.

She opened the waterproof file. Inside were printouts and screenshots. The first page was titled GachiSum admin access.

GachiSum.

Ji-an knew the name. A safety location-sharing app used by women living alone and by families caring for elderly parents. It had once been covered in the press as a good example of protective tech. Su-bin had mentioned it before, saying she was thinking of installing it in case their mother wandered in the early stages of dementia. Ji-an had only half-listened because work had been busy.

The first page showed an administrator ID and a list of permissions. Real-time user locations. Deviation alerts. Frequent routes. Even summaries of accumulated daily routines. Framed as safety features, yes—but in the wrong hands they amounted to a complete map of a person's life.

The next pages were screenshots of message threads.

204 in Building 5 still isn't home.
301 went to the hospital and came right back.
That woman goes to the convenience store at two in the morning.

The sentences were so short and flat that they became worse. The people in them were not being discussed like people. They were moving markers. Targets. Stock.

Su-bin had seen this.

At the bottom of the bag lay a small notebook. On the first page were three names.

Eun-seo / Building 5, Unit 204 / hiding
Kim Jeong-ae / 301 / nighttime wandering
Su-bin / checking

Ji-an turned the page. Short notes continued.

Eun-seo is hiding from an ex-boyfriend. If her location leaks, she's finished.
Grandmother Kim Jeong-ae is being pushed over redevelopment consent. Brokers arrive before her son does.
One of the GachiSum admins is connected to the Dongmun district field office.

At the bottom of the page, written with a heavy hand:

If you read this, pick one person you can trust before anything else. Don't carry this alone.

Ji-an bit down on her lip.

At last the shape of what Su-bin had feared in Dongmun was becoming visible. It had not simply been a place she disliked. It was a neighborhood that resold the footsteps of people who had run there to hide.

She powered on the backup phone. The wallpaper was a family photo from their mother's birthday. Ji-an's heart lurched. Their mother had been dead for two years. In the picture, Su-bin was smiling as if none of this would ever happen.

The message inbox was empty, but recordings and memo files remained. The memo app held date-stamped lines.

7/4 Grandmother Kim disappeared before the report was filed. Two brokers arrived first.
7/9 Eun-seo's location leaked. Need internal GachiSum confirmation.
7/11 Can't tell unni. She'd jump in immediately.

At the last line Ji-an shut her eyes for a moment. She wanted to be furious. Why didn't you tell me? Why did you carry all of this alone until you died?

But before anger came something else.

Su-bin had been trying to protect her.

She had known exactly who would run straight into the fire if told.

Ji-an opened an audio file. Wind. Footsteps. Hard breathing. Su-bin's voice, almost a whisper.

We installed GachiSum to keep from losing Mom. But it wasn't being used only to find people.

A short silence.

They're selling who is alone, when they're weakest, where they'll be.

That was all.

Ji-an lowered the phone numbly. The app they had once considered installing for their mother was not a net holding people together; it had become a tool for extracting the vulnerable moments in their lives.

Then a movement in the reflective glass of the corridor caught her eye.

Ji-an killed the screen at once.

Someone in station uniform—or maybe cleaning staff—passed slowly by the lockers. It could have meant nothing. Yet the person glanced once, very briefly, toward B-18. That was enough to send a cold thread down her spine.

She packed the bag and hurried toward the busier end of the station. Even among more people, her heartbeat would not settle. Had she already been noticed? Had opening the locker triggered something somewhere?

She sat on a bench outside the station and started sorting the documents again when the backup phone vibrated by itself.

Ji-an froze.

A map opened on the screen. This time it was not current live tracking but a saved final route. A green dot hovered over an aging villa block a short distance from the station.

Serim Villa 301.

The same place written in Su-bin's note.

At the same moment, Ji-an's own phone buzzed.

It was not a blocked number. It was an ordinary mobile number. That made it worse.

The message contained one line:

You're still following that location? Stop now, and this ends with the funeral.

Ji-an stared.

Ends with the funeral.

That was not a vague threat. It meant the sender already knew Su-bin was dead, and also knew Ji-an was following the route she had left behind in real time.

Her fingertips shook. Police. Reporters. Lawyers. The words collided in her head. So did Su-bin's note: choose one person to trust first.

But before any careful decision came something simpler.

She had to go to Serim Villa 301.

Whatever Su-bin had hidden there would be the real final thing. Probably also the answer to why she had left her location share alive beyond death.

Ji-an stood up slowly. Dawn was beginning to gray the edges of the city, but inside her body it was still night. She had thought the crowd might dilute the fear. It had only made it sharper. Now she could almost feel the shape of the hours Su-bin had spent carrying this alone.

She pushed the backup phone and the file deep into her bag and buttoned her coat over them. Then she looked again at the message on her main phone.

The sender did not seem to want a reply. It was enough for them that Ji-an knew she was being watched.

She did not save the number. She only took a screenshot and sent it to the backup phone. From here on, it felt as if even one dropped piece could cost too much.

Don't carry this alone.

The line kept repeating in her head.

Ji-an took two steps toward the platform and stopped again. Go straight to Serim Villa, or stop first and find someone to trust? She still did not know which was right. She only knew that time was not on Su-bin's side anymore.

The station clock switched over.

5:14 a.m.

Su-bin's location, even after death, still had not turned off.

But from here on, no one could guarantee Ji-an's safety while she followed it.