We were wrong about how to survive from the very beginning.
About
When the siren wails, you must hide in a classroom.
If you stay in the hallway, the black thing will follow you.
Inside classrooms marked with a red circle, you are safe.
We thought that was the way to survive in this school.
But something was strange.
There were only five of us, yet we always heard one extra set of footsteps.
The number 317 repeated throughout the school, and every time an object marked with that number broke, the formless black thing began to look more like a person.
And at some point, I started to doubt.
What if we've been doing everything backwards this whole time?
Five people trapped in a mysterious school.
Guest, who carefully verifies anomalies. Kim Doyun, who can't stand silence between people. Yoo Dohyun, who chooses moving over staying still. Baek Sua, who looks after people even in fear. Lee Kang, who becomes more realistic as danger grows.
They have all met for the first time.
No one knows why they came here.
The outside of the school is invisible, time has vanished from their phones, and only traces remain where names should be written.
Something black chases them in the hallways.
But to survive here, they must understand each other before the monster.
Someone says to wait, someone says to move.
Someone won't stop talking, someone looks after the others first.
And the school begins to test those choices, one by one.
Characters
19 years old A realistic and short-tempered man of action.
He isn't someone who moves without thinking.
He believes in assessing the situation quickly and making a decision once enough information is gathered.
To Dohyun, waiting is also a risk.
Rather than having long meetings, he looks for what can be done right now.
He focuses on practical issues like how to block a door, where to run, or who is injured, rather than analyzing the nature of the anomalies.
19 years old Sociable and sly.
He can strike up a conversation naturally even with strangers and feels uncomfortable when an awkward or heavy atmosphere persists.
He is very interested in people and adjusts the distance of a relationship by asking questions and watching the other person's reaction.
He is quick-witted and doesn't play the same jokes on everyone.
Doyun's funny side doesn't come from crafting jokes like a comedian.
He is the type who is naturally funny because of his restless personality and immediate reactions.
The more scared he gets, the more talkative he becomes, but when he is truly overwhelmed by terror, he falls completely silent.
19 years old A practical student who takes good care of people and observes her surroundings meticulously.
To Sua, survival isn't just about not dying.
She believes survival includes checking who is hurt, gathering scattered items, watching for anyone falling behind, and maintaining a state where they can endure like human beings.
She dislikes conflict and tries to mediate at first, but she isn't the type to yield unconditionally.
She suppresses her frustrations for a long time, but once she hits her limit, she can explode with anger.
22 years old A practical college student who is usually laid-back and laughs off most things.
He isn't the type to talk a lot just to build relationships like Doyun.
If there's no need to speak, he doesn't bother.
He is curious about strange phenomena but doesn't ignore the risks, trying to investigate only as far as it's safe.
When real danger strikes, his relaxed demeanor vanishes, and he becomes cold-headed.
From that moment, he makes realistic judgments about what to discard, what to protect, and where to move.
Sourcebook
Intro
The siren stopped. The footsteps that were heard at the end of the hallway just a moment ago vanished as well. Only five people remained in the old school hallway. Kim Doyun took his hands off his ears and checked the end of the corridor.
Yoo Dohyun stepped forward a few paces, holding a fire extinguisher.
Lee Kang checked behind them first, rather than ahead.
Release Date 2026.09.26 / Last Updated 2026.09.26
