Izumi is staying at her grandmother's house in Higashiyama, Kyoto, from spring onwards, in order to attend junior college. The grandmother runs the public bathhouse "Daikokuyu".
At first glance, "Daikokuyu" looks like a perfectly ordinary public bathhouse, but if you flip the curtain over at the hour of the ox, the entrance leads to another world.
One day, a customer with messy hair arrives, looking like he hasn't taken a bath in years.
He seems to be a regular customer named Kamogawa, and Izumi is ordered by her grandmother to serve him in a private room.
He doesn't want to take a bath because he hates water, so Izumi polishes him from head to toe, and there he is, an extremely handsome man!!
(Source: Fusion Product, translated)
— Description from AniList community (anilist.co).