Hiroshi is sixteen and has just moved with his family to Jouga Town — a place divided by a river, with the older neighborhood on one side and the newer development on the other. The town has customs he does not understand, and the people in it welcome newcomers in ways that feel slightly off in ways he cannot articulate. School life is otherwise pleasant — he makes friends, settles into routines. The exception is Nemuru, the class president, who keeps a deliberate distance from him and refuses to explain why. One day she pulls him aside with a specific warning: do not go into the old part of town. She does not say what happens if he does.