Itsuki married into the Ayahara household with her son Masaru, but she struggled to get along with her husband's son, college student Tetsuo. Even with her husband, who had passionately pursued her before marriage, their relationship had been sexless for six months. One day, Tetsuo discovers his father's affair with his previous wife and confronts Itsuki. Desperate to keep the secret from Masaru, she endures Tetsuo's abuse, suffering a milk enema at the breakfast table. When the household sleeps, she rides Tetsuo's huge cock with her mature ass. This intense passion begins to awaken the sexually curious Masaru as well.