A Secret Virgin's Break

 "A Secret Virgin's Break"  Himitsu no Vuājin Bureiku ヒミツのヴァージンぶれいく)   is the first episode of the Imouto Paradise! 2 OVA. It was released on  August 3, 2013, produced and directed by studio Mary Jane.

Full Summary
Keiichi accidentally walks in to Ririna who's body is rather exposed, ultimately leading to him getting a beating from her. Afterwards, Momoka gives Keiichi a very suggestive massage which he enjoys very much. Ririna lectures Keiichi to learn to knock on a girl's door before entering her bedroom. Keiichi makes a perverted comment, leading to him receiving yet another beating. Ririna tells him to start acting responsibly, and to stop making vulgar jokes, before Keiichi reveals he knows about her masturbating. He knows this because after he went in the show after her the previous day, he found a sex toy. She asks him what he's going to do, if it were to belong to her. In order to keep this a secret from the others, she must do whatever Keiichi desires, which includes having sex with him, which she secretly enjoys, despite she tells him that there is no good or bad about it.

Later that day, Ririna is shown giving Keiichi a massage similar to the one given by Momoka, and she reminds him that he has to keep it all a secret, which he reluctantly agrees to. He also tells her that he wanted to satisfy her, she responds by saying she will never forgive him, and that she will definitely make him take responsibility. The episode ends after she gives him a painful reflex, with a satisfied smile.