He is a Squirrel who usually sits on Hideto Mitsu's shoulder.

Spoiler

Reincarnation of Akechi Mitsuhide, a samurai and general who lived during the Sengoku period of Feudal Japan. Mitsuhide was a general under daimyō Oda Nobunaga, who then became famous for his rebellion against Nobunaga in 1582, which led to Nobunaga's death at Honnojui.