Yuki and Souta, who were classmates at a vocational school, were still virgins with no dating experience.In order to plan their graduation work, the two of them came to a hot spring inn deep in the mountains, where they usually have nothing to do with each other, but where it seems quiet and where they can concentrate.Sayako Sanada, a virgin-loving woman traveling alone who is looking for a once-in-a-lifetime encounter, has come to the inn.