His mother Yuri seems to be lonely these days. Shinji is trying Kokoro best to cheer her up, but one day he witnesses Yuri masturbating. To fill his mother's loneliness, Shinji decides to embrace Yuri in place of his father. Yuri, realizing that this is Shinji's way of showing kindness, accepts the forbidden relationship, but... Shinji is a virile man. Even after Yuri has exceeded her limits, Shinji's thrusts continue endlessly.