Illusion prison

Illusion prisond (錯覚の刑務所 Sakkaku no keimusho) is a prison to command the hidden magic council. Several years that will kidnap several women and several man to work in search of material to build a magic weapon skins to control the world. It is located underwater in the middle of the North Ocean.

Description
The prison resembling a rock formation that appears to be floating in the middle of the sea.

Trivia

 * This is the world most secure prison, with only Crevan Sytiki escaped by an unknown mean fooling even the Cobra, who attempted a suicide on hearing that.