Saya was instantly shaken the moment she laid eyes on Yuki, her son's classmate. His appearance was nearly identical to a man she once loved, and upon realizing this, Saya couldn't suppress her shock—Yuki was that man's son. Watching her mother treat Yuki as a substitute for her lost lover, the son is overwhelmed with loneliness, anger, jealousy, and distrust, driving him toward his mother's bedroom.