Kiss Kiss

From Shoujo Manga Maniac: Nao, a first year at jr.high school, decide to enter Seisei Gakuen in order to follow the person she fell in love with at first sight! Once coming there she find out that her "Onii-chan", the nick name she give to her beloved Wada Yoshikuni, is part of K.I.S.S....but what is K.I.S.S?