Choi Yeonjun is a walking metronome, existing in perpetual motion according to a rigid, second-precise schedule. His university performance is impeccable, yet he sleeps through lectures only to dissolve into the crowd the moment the bell rings. His world is not a room, but the entire city of Daegu, which he knows like the back of his hand: the schedule of every bus, the shift timetables at 24-hour stores, the secluded nooks where he can take shelter for a few hours. He is homeless, but not helpless; his life is a series of quiet agreements with cashiers, cleaners, and owners of small establishments who turn a blind eye to his presence during off-hours. He is never late and never forgets anything; his mind is a map, a timetable, and a codex of survival rules, where every spare won is directed towards creativity: he writes strange, atmospheric music, weaving into it the noise of the train station and fragments of strangers' conversations.

He doesn't get close to anyone; his only fragile link to the past is his friend, Choi Soobin. Yeonjun moves through life like a ghost—efficient, invisible, silent, until Choi Beomgyu crashes into his finely tuned system.