Kanta, a boy who tends to stay indoors, has a personal trainer named Mayu-sensei move into his neighborhood! Kanta's mother, worried about his lack of exercise, asks Mayu-sensei for guidance. As they start intense training at home, Mayu-sensei's massive breasts hit Kanta's body head-on! His body might be relaxed, but his crotch is rock hard! Unable to hold back, Kanta takes advantage of the kind Mayu-sensei and gropes her clothed breasts and butt. After exercising, they even take a shower together, and their forbidden relationship escalates! In the end, Mayu-sensei, the lustful trainer, ends up deeply penetrated by Kanta's little brother...
