4 sisters inherit a hot-springs Onsan from their parents who passed away in an incident. They take over the Hot springs business, but things are tough and not smooth. So basically, they decide to offer sex in the Hotsprings menu, effectively converting it in a whore-house?. Yeah. But it saved the business!.
Also, I recognized Kazama Rina in there, good thing that she still has a job. Lol.