The purpose of a fun school trip isn't just sightseeing! When he sneaks into the girls' room at night and dives under the covers, the girl he likes greets him in a more seductive yukata than usual! They're both excited! They lose all sense of reason and start having sex! Although they're hiding under the covers, the suspicious movements of the covers definitely stimulate the other students, and before they know it, it's a drunken orgy, and a miraculous night has developed into a big one!