The students in the countryside secretly take a bus left behind at the back of the school and do something stingy after school.

An old bus thrown away in the back of a school. It looks dirty inside, but it rains, and I can't see anything more than that. The bus is perfect for a secret base, and it's just a hideaway for boys who smell blue. And the thing to do in a hiding house is Etchi. Moreover, since there is nothing to do in the countryside, everyone is quick and pure but its concentration is also dense!