Fumi is cleaning as usual... However, what's different from usual is that her husband has gone on a mahjong trip, and her son Kazuhiko has been sent out to help with farm work at her parents' house, leaving her alone. One day, Fumi, taking advantage of the fact that no one is around, indulges in masturbation with an extra-thick adult vibrator... A figure peeks at her from the garden... It's Kazuhiko's childhood friend, Tohru. Tohru, who is trying to kill time by peeking into Kazuhiko's house from the garden, witnesses his beloved aunt thrusting an extra-thick vibrator into her vagina and writhing in pleasure. Tohru plans to have sex with the aunt, and pretends to be a coincidence and appears in front of Fumi...