Issei Hyoudou and Rias Gremory.

Issei couldn't believe it for years he's tried to lose his virginity to a beautiful girl and finally that time has come to think that he Issei Hyoudou would get to have sex with one of the hottest girls in his school not only was she beautiful but she was also completely fine with his dream of having a harem. Unknown to Issei though was that the reason Rias was so fine with him having a harem was because all female supernatural creatures had a secret that the men of the world wouldn't learn of until it was to late to do anything about it.

So while Issei was jumping for joy at the thought of losing his virginity to a real woman Rias was plotting on how she was going to introduce Issei to her big secret as well as fantasizing about what she was going to do to him and his tight ass.