It is sex as for preaching Mr. Nakai who came to the bedding in the hot spring inn. Part of the scene is secretly taken by the camera. 3

Setting up a hidden camera in the room at the hot spring Inn of the reputation that Nakai of beautiful woman is there. It is the third shot of the camera captured by the camera when Nakai visited the room to put the futon and was persuaded by the guest (actor) and Nakai falls.