Some terms and explanations :
A realm specifically made to keep and torture evil spirits for eternity. Where all the Devils come from. For several hundred years they train at the Devil Academy, after which they’re assigned to a certain Branch within the Hell Society.
Spirit Countermeasure Branch
Led by Dokurou Skull, the SCB is responsible for sending out Devils (usually tied to a human partner) to Earth to capture Evil Spirits that escaped from Hell.
The highschool that Ryoushi and most other characters attend.