I'll never get bored reading stories of tsundere girls doing all the perverted stuff because "you blackmail me, so we gonna have sex. It's not like I like you or anything..."!
Warped, huh...
A little bit, perhaps, but it is Hentai after all so it fits quite nicely, I would say.
So if the girl you're blackmailing doesn't seem to be giving in to you, the next step is to go for anal? Interesting...