Koakuma to Meromero Tengoku

Otomaru is out drinking with her boss and the next thing she realizes is that she's in a love hotel with him. This frightens her to no end and she just wants to leave, but her boss is persistent, and it turns out he's a very good lover. So they become friends with benefits in secret, as she's shy and he's most definitely not. But what Otomaru hasn't yet figured out is why her boss keeps coming back to her...