The greatest Onmyouji in in the history of Japan, Abe no Seimei is the grandfather of Masahiro. He has Twelve shikigami under his command and is able to transfer his soul (which is in his younger form) outside of his old aged body, but this makes his body vulnerable. He teases Masahiro to push him further in his journey (which is kind of like a reverse psychology) and helps him out when he is in trouble. Masahiro calls Seimei "Old raccoon" when he is angry after Seimei's lecture/teasing of Masahiro's performance. (Source: Wikipedia)
Masahiro's mentor and friend.
Genji's wife through an arranged marriage, daughter of the Minister of the Left and younger sister of Genji's friend To no Chujo. She is cold and unfriendly towards Genji; his many love affairs are an affront to her pride.
Makoto's father. A salary man who does a lot of overtime though he has no chance of getting promoted.
He likes penguins. He was controlling Kyoko and speaks through her to Ayumu and co. He is very interested in Eu. Eu had said she told him to "disappear" and, while he did, but not from this world. He later seeks out Eu to request his death. Manipulating her anyway to accomplish his goal.