Yamada and the Seven Witches (OVA)

Shiraishi Urara is the top student in her school. One day, due to an accidental kiss, Urara finds herself in the body of the school delinquent, Yamada Ryuu! In trying to switch back to their own bodies, Urara and Ryuu discover that kissing causes them to switch bodies, which leads to their discovery that there are 7 witches in their school. They soon try to uncover the identities of the 7 witches... (Source: AniDB)