When his wife's mother came to Tokyo and left the house empty, the son-in-law began living alone with his stepmother while his wife remained in the hospital after childbirth. Concerned about his hospitalized daughter, the stepmother's presence created more private time between her and the son-in-law. Under the pretense of helping with household chores, the son-in-law gradually draws closer to his stepmother. Meanwhile, the stepmother finds herself emotionally stirred by her young son-in-law. The growing feelings between them begin to blur boundaries, raising questions about how this connection will transform their relationship.