Rabou is an enigmatic character and appears in the manga special "Clash, O Ye Gods of Calamity" as well as in the anime, though his role in the anime does not follow the chronology of the manga special from which he is derived. He is often seen conversing with the Nora shinki who is involved with Yato, and has been known to be able to control Phantoms. He has some unknown past with Yato, and seems to harbor a grudge against him. He is also known as a God of Calamity, similar to Yato. He is known to kill humans, shinki, other gods, and phantoms, not caring what the job is, as long as he was wished to do it.

(Source: Wikipedia)