Rei Kurorogi

A man who invited technology that enabled him to port his consciusness to another body. [Spoiler] He is the true mastermind behind everything, and the creator of both Wataru and Wataru Himeji. [/Spoiler] [Spoiler] Keito Makabe is one of the many people whose bodies and identities he has possessed, including that of Koumei (Eris's husband) and Shinobu's mother (who was an exorcist). [/Spoiler]