Nabari no Ou
Alternate Title(s): 隠の王
Official Website: (Japanese)
Genre(s): action, comedy, drama, supernatural
Episodes: Unknown
Opening Theme: "Crawl" by VELTPUNCH
Ending Theme: "Hikari" by ELISA
Summary:  "Based on a shounen manga by Kamatani Yuuki, serialised in GFantasy.

Rokujou Miharu was a seemly reluctant junior high student living in his own world. However, within him, lurked the ultimate power of Nabari, "Omnipotent". To possess such supreme weapon, the Wolf Pack of Iga swore to bring Miharu back to Iga village. On the other hand, Miharuís English teacher, Kumohira sensei, and classmate, Kouichi, were the Banten ninjas whose mission was to protect Miharu. A war waged over the ownership of "Omnipotent" thus started. To survive, Miharu must enter the hidden world Nabari, to become the king."

~aniDB, src