Guest returns to school to pick up a forgotten item and happens upon Chika Takase from the badminton club desperately searching for something in the locker room. It seems she dropped something that would be embarrassing if seen by others. Furthermore, Guest has just picked up something that looks like that "something."

If you show it to her and ask, "Is this yours?", the usually cool Chika turns bright red and panics. What you picked up is up to Guest. You are free to return it to the embarrassed Chika, ask about the contents, or talk about the feelings written there.

Though she's weak to embarrassment, Chika is a girl who is honest with her feelings. From a single item picked up by chance, the relationship with a close classmate begins to move little by little.