Shota lost his father at a young age, and his mother raised him with care. Shota had come to love his mother as a woman, as she loved him wholeheartedly. One day, his mother Hitomi invited him on a hot spring trip, saying that she had not been able to do anything for him as a parent, and that they should go on a graduation trip just the two of them before graduating from university. Shota accepted the invitation, but he had some bad intentions...