On a weekend off, office worker Shintaro, who normally keeps busy working in Tokyo, finally gets a rare extended break. He and his wife decide to visit her parents' home in the countryside. After a three-hour journey by shinkansen and local trains from Tokyo, they arrive at a traditional Japanese-style house in a mid-sized city undergoing urban development. There, his wife's mother, Natsuko Kayama, warmly welcomes them. As soon as he sees his mother-in-law's voluptuous figure, Shintaro catches his breath, his heart suddenly racing. The quiet days at this rural home are about to become the beginning of a thrilling new adventure.