Today, I went to a public bath with my sister-in-law.

Manji, a ronin student, lives alone in an apartment without a bath. One day, his sister-in-law Harumi ran away from home and moved into Manji's room. Harumi heads to the public bath, ignoring Manji who is confused. Harumi, who has always been a familiar customer, asks the owner, Sasaki, to let her take a bath before the store opens. However, after having too much fun at the public bath for the first time in a while, Harumi gets dizzy and can't move. Manji rushes to help, but then female customers come in...