|Onigashima Elementary School|
|Located in||Ogre Island|
Onigashima Elementary School also know as the Grade School's Penitentiary, is a school where problem children from all across the country are sent to. Being transferred to Onigashima is the most severe punishment a student can receive if proven guilty in a classroom trial.
Onigashima is located on an island, dubbed Ogre Island, and is presumably isolated from the rest of the country. Despite this, it is not completely cut off from the world, as Abaku Inugami explained that he was still able to see his family during his time there.