Help me please

I've actually read a manga but I forgot the title .... for those who have watched the anime wotakoi .. when the four of them went to a 'bookstore' which was actually a manga store .. there was a picture of a manga in the elevator that was a man and a woman. If you guys know the title please tell me .. I really forgot the title. The story is about a high school woman who has a friend and her friend has an older brother and her brother is a playboy and her brother likes the high school woman.