From Yen Press:

The "Roman Club", a school group interested in the occult, to which he's practically enslaved, has become boring for one Hideo Aiba. In fact, he finds his entire existence pretty tiresome until, one day, when a girl named Kurumi Sahana shows up and wants to join up. When the two are left alone in the club classroom, Kurumi makes a special "request" of Hideo, which makes him (understandably) freak out. Though he doesn't know what to think, one thing’s for sure, Hideo’s life just became anything but boring.

There is something a bit twisted inside of the teenage girl Madoka. It comes out one day when she has to deal with a groper on a public train. He may be scarred for life by the time she's finally through with him. But for her, at least, this encounter may only be the beginning...