Asagi’s bodyguard. In the anime, Natsume calls him Janome-san (蛇の目さん) when he refuses to reveal his actual name. Janomegasa are a type of traditional umbrella Youkai - Janome alone however simply means one-eyed.
In the manga, Natsume calls him "Mary" from Mary Poppins because of the umbrella. His name is not contained in the Yuujinchou.
History
He's been the umbrella carrier for notable youkais that visited Mibu-sama. One of them is the pretty Asagi, whom the famous koto player at the Isozuki Forest.
Asides from carrying umbrella for Asagi, Akagane also acts as her bodyguard, saving her from any nasty youkai that want to trouble Asagi.
Personality
He is willing to do anything to make the koto for Asagi.