Two years after losing her husband, Iroha finds her daughter returning home married and moving in with her new husband, forming a new trio household. One day, Iroha accidentally spies on her son-in-law masturbating and, though surprised at first, reasons that it's normal for a young man. Later, when left alone together, she overhears him confiding about marital intimacy issues with her daughter, and they both realize they've been secretly watching each other masturbate. Claiming they'll only touch each other's hands, they end up entwining their bodies. Hidden emotions quietly stir within their everyday lives, slowly blossoming into forbidden desire.