Age: 25 years
Birthday: 3/17 (17 March)
Height: 186 cm
Weight: 73 kg
Shoe size: 29 cm
Blood type: AB
Likes: Gardening, Bacon Bagel
Dislikes: All Vehicles
Specialties: Pretending to be out, Seal Cancel Technique
Birthplace: Waterford, Ireland

Rokujo's and Kouichi's 25-year-old english teacher in the "front world".
Born in Ireland on March 17, Kumohira is actually a ninja of the Banten village in the world of Nabari. He is entirely devoted to protecting Rokujo, and wants him to become the ruler of Nabari. He has an intense hatred of transport, such as trains and buses, and would not get on one until Miharu manages to "persuade" him. He went to Japan because his grandfather was a "Japan otaku" and "ninja fanatic", who forced him to go to learn to become a ninja, and was unable to return home for ten years (partly due to his phobia of vehicles). It was during this time that he became the Rokujo family's close acquaintance, the memories about which Miharu has lost after an incident concerning the Shinrabanshou and its user (who was either Miharu's father, Akatsuki Rokujo, or his mother, Asahi Rokujo) killed his parents and Kumohira's grandfather and erased the concerned individuals' memories about it, except Kumohira's himself, 10 years ago. In the anime, he is the temporary leader as the current leader is away, while in the manga, he is not just a stand-in, but actually has the power to arrange for a temporary leader. According to Aizawa, Kumohira has probably recorded Banten's kinjutsu through verbal communication.

Among the Banten ninjas, Kumohira is the most vehement dissident against Miharu using the Shinrabanshou, instead advocating its permanent seal. This often results in him going to great length to dissuade Miharu from attempting to activate it, which clashes with Miharu's promise to Yoite. After realizing Miharu's determination to fulfill his promise, Kumohira went into hiding to conceal the whereabouts of the last kinjutsushō, Banten's Engetsurin, from whoever trying to find it.