Kure-nai (2008)

Shinkurou Kurenai is a 16-year-old student by day and a dispute mediator by night. Despite his unimposing appearance, he is a strong martial artist, who also possesses a strange power. While taking various jobs for his employer one assignment leads Shinkurou to live with Murasaki Kuhouin as her bodyguard. Murasaki is the seven-year-old daughter of a wealthy family, who escaped from her home under strange circumstances.