Keiichirou is a shy, sweet boy who is very lonely. He became a good friend of Amanojaku, and sometimes took him with him to school. Keiichirou really misses his mother. He also loves his older sister Satsuki and his father although their family is strained by their lack of a mother. Keiichirou seems to be easily scared and cries very easily. Whenever Satsuki is threatened by a ghost or their father is in danger he appears to worry he is going to lose another family member and becomes distraught.
Keiichirou is portrayed as naive and immature and rather clumsy at times, he is often described as a "crybaby", however he develops emotionally over the course of the series, even coming to accept his mother's death.
In the ADV dub, Keiichirou is constantly refered to as retarded and tends to spout gibberish to support that.
Keiichirou is very attached to the family pet Kaya. When the cat becomes possessed by Amanojaku he still calls him Kaya while the rest of the cast address him by his demon name, this perhaps endears him to Amanojaku and contributes to their friendship. He is also a good friend of Hajime and Leo and seems to see them as his "older brothers". He also likes to play with Momoko. Keiichirou is shown to be good at befriending spirits without really meaning to as he makes friends with Datto and Amanojaku.