Astaroth, also called 'The King of Rot', is a Demon King who attached to the body of a rich young boy. He refers to Rin as 'his young master', probably a reference to Rin being the son of Satan.
He is capable of repossessing a body after being exorcised as evidenced when he repossesses the boy after being expelled by Fujimoto
In The AnimeEdit
He first appears in Episode 2 when threatening to blind Rin with a heated pole to reveal Rin's powers. He is then exorcised by Fujimoto although he repossesses the boy shortly after. A seal of binding is then placed on the boy to prevent a third possession although it is yet unseen if this is successful.
When possessing a human he appears as the host human with fanged teeth and ram - like horns on his head. His eyes become red and pointed. He also has a tail similar to Rin's and pointed ears. His voice also becomes deeper and crueller than when his human host is in control.
- Astaroth (also Ashtaroth, Astarot, and Asteroth), in demonology, is the Crowned Prince of Hell. He is a male figure named after the Canaanite goddess Ashtoreth.
- in the Dictionnaire Infernal, Astaroth is depicted as a nude man with feathered wings, wearing a crown, holding a serpent in one hand, and riding a beast with dragon-like wings and a serpent-like tail.