Nabari no Ou (2008)

Friend and foe prove difficult to tell apart.

In the shadows of this world, ninjas fight for control of an ancient technique which holds untold strength. This coveted power dwells within apathetic Miharu, a fact the guy really couldn't care less about - until the rival clans bring their battle to him. Now, he must choose a side if he hopes to survive - but when conflict is waged in secret, friend and foe prove difficult to tell apart.