Keikain Aki is one of the female protagonists of Devil's Rising. She is a Human (Shinto Priest)/Nine-Tailed Fox Hybrid, who is the eldest daughter of Kyoto-Youkai Faction's leader and head of certain famous Japanese Shinto Exorcist family who are said to be the direct descendant of Abe no Seimei. After she met Nicholas and his peerage during their travels in the Oustergraht, under both Nicholas's persuasion (in this case, flirting) and twist of fate, she became a Reincarnated Devil under his peerage and joined the Varia Criminale.