Momonari Hyakuhachi, the son of Risono in Otama City, is a high school freshman
who is so active that he masturbates in a hole in the ground. One night, the wife of Oshiro Department Store, who does business with Rion, sees his behavior and is told to stop doing business with him because it is so vile! It was such a horrible encounter, but gradually the distance between him and Mrs. Oshiro grows. Shrinking, he gets to know a woman's body for the first time...