Yuki and Sota, classmates at a vocational school, had never had a romantic relationship and were still virgins. To plan their graduation project, the two of them went to a hot spring inn deep in the mountains, a place they usually don't visit, but where they thought it would be quiet and they could concentrate. At the inn, they met Sayako Sanada, a woman who loves virgins and is traveling alone, looking for a once-in-a-lifetime encounter.