Shuuji is employed by the Koigakubo family as Himeko's bodyguard. They go to the same school, but Himeko is older than him, so they're in different grades.
Shuuji hates violence and wants to destroy it. He uses Himeko, who only falls in love with violent people, to try to fulfill this wish. He has an older sister who always protected him from their abusive parents.
