A teenage boy is suddenly pulled from modern Tokyo into a fantasy world with nothing but a convenience store bag and his wits. After a chance encounter with a silver-haired girl on the run, he discovers he has a strange and painful ability: every time he dies, time rewinds to a fixed point, forcing him to relive events from scratch. The series builds a tense, emotionally layered story around what it actually costs to keep trying when failure means death, and death means starting over.