Hibiki and Naoya are step parent and child. Hibiki has been trying to fulfill her role as a mother, but Naoya, a young man coming of age, finds himself captivated by her beauty. He begins to see her as a woman, and the pain of suppressing his feelings grows unbearable. Unable to endure the emotional strain any longer, Naoya decides to leave home. As a final farewell, the family of three embarks on a hot spring trip, where Naoya resolves to sever his forbidden emotions for Hibiki.