The Gentlemen's Alliance Vol 3

The Gentlemen's Alliance Vol 3 by Arina Tanemura. A Shojo manga rated Older Teen, published in English by Viz Media in 2007.

Haine Otomiya, a former delinquent, is adopted into a rich family and enrolls at an elite academy with a rigid social ranking. She has loved the student council president, Shizumasa Togu, since childhood, but he is hiding secrets of his own. From Arina Tanemura.