Goro is a father of two who married Yuka three months ago, beginning life as the new son-in-law in the Kuroki household. However, she starts feeling uneasy about her husband's strange sexual habits and the sons' lingering gazes. One day, she discovers her underwear soaked in semen and is subsequently assaulted by the younger son. As the eldest son approaches his 27th birthday, the gift Goro prepares for him draws near…