Des：Shiro is a complete mothers boy, and went on to university within commuting distance from his home. Furthermore, his sexual interest only arises in his mother, Rie. Rie is in her prime, but in her heart she wants to have a sexual relationship with Shiro even more than her husband, who is in a state of no sex. Today, Rie and Shiro are going on a hot spring trip alone. Rie was a little worried that she might end up with Shiro on this trip...