Otouto wa, Ookami.

Beitofuku's father remarried a week ago and her step brother turns out to be the school's most popular guy, Aizawa Hiroki. Giving the appearance of a gentleman it turns out he's a huge playboy, trying to "capture" her to prove they can't be a family!? Included one-shot: Kanzen Date Manual (完全デートマニュアル); Betsucomi 2009-09 Ichikawa can never seem to stay as a lover with anyone she goes out with. To help solve this problem, she gets her popular male friend, Sugiyama, to go out on a date with her to point out where she always goes wrong?! Source: My Anime List