While mother Shiho continues to treat her son Yuuichi like a child, Yuuichi leaves the shower without properly covering himself. One day, after returning home, he finds Shiho still in her post-shower attire. Unable to contain himself, Yuuichi begins masturbating in his room—only for Shiho to catch him in the act. Overcome with desire, he suddenly lunges at her. Though their relationship had been strained, everything changes when Yuuichi accidentally discovers Shiho masturbating one day.