Benimaru

Age unknown.
Likes: Meat
Dislikes: Idiots

Aoi's shikigami, he's served her clan for hundreds of years. He usually dwells in a red sword.
He's actually a demon who eats humans.
He has a bad mouth and often calls Aoi an idiot.
When Aoi was summoned to the other world he mysteriously disappeared.

Spoiler

(CV. Okiayu Ryoutarou)