Nabari No Ou Vol 1

Nabari no Ou by Yuhki Kamatani. An Action manga rated Older Teen, published in English by Yen Press.

Apathetic middle schooler Miharu Rokujo wants nothing more than to be left alone. Unfortunately, he carries within him the Shinrabansho, a secret art so powerful that every ninja clan in the hidden world of Nabari wants to claim it, and him.