A young man who has lost his memories finds himself in a world where the gender ratio is 1 man to 100 women—a world where traditional gender roles are reversed.

There, he's taken in by Misago, the daughter of a hot spring inn. She gives him the name Hisui, and he begins living at the inn.

Of course, he can't keep living there without contributing anything forever. So the job he's given is... to work as a sansuke, a male bath attendant responsible for washing female guests' backs.

Hisui quickly adapts to this gender-reversed world and settles into a happy life at the hot spring inn. Meanwhile, the girls who find themselves constantly caught up in his antics gradually begin falling for him.

This is a heartwarming harem ensemble story about Hisui and the girls, set in a rather unusual hot spring inn.