A family-run hot spring ryokan known for its hidden hot springs deep in the mountains.However, his parents died in an accident. The four sisters decide to inherit the inn, which is also a memento of their parents.However, they did not have the ability to run an inn, and they were driven to the brink of bankruptcy.However, they make full use of their boasted big breasts, and a project SEX story to rebuild a splendid inn.