The Tsukiyomi royal family have been receiving threats on their lives. As a result King Aruto, requests the help of his long time friend Tsumigu Hinamori and his family who happen to be trained assassins. Prince Ikuto seemed to have become quite interested in Tsumigu"s eldest daughter, Amu Hinamori and doesn't mind that she has to to play the role of his girlfriend to avoid suspicion at Royal Seiyo Academy , a school for rich kids . While Kukai, Amu's older brother becomes smitten with the young blonde haired Princess Utau, all while Saaya and Tadase try to earn the interest of royal siblings.