Nabari no Ou(2004)

Nabari no Ou

Apathetic schoolboy Miharu Rokujou is content to meander through life in the sleepy village of Banten. But his quiet existence is shattered when the Grey Wolves of Iga, a powerful ninja clan, attempt to kidnap him in broad daylight. Only then does Miharu discover that the ultimate power of the hidden ninja realm - a power that can do both great good and great harm - is sealed within his body. As battles erupt among rival ninja clans seeking to control him, Miharu must overcome his apathy and learn the ways of the ninja if he wants any shot at survival!

(Source: Yen Press)