Tarou Sado has been a masochist since middle school, ever since a punch from his classmate Arashiko Yuno left him strangely pleased rather than hurt. His friend Tatsukichi Hayama, who doesn't judge him for it, points him toward the Second Voluntary Club and its president, the self-proclaimed goddess Mio Isurugi, hoping she can cure him. Instead, Mio's rough treatment of Tarou only makes his condition worse, tangling the two of them together as she keeps trying anyway.