"Prison Break" 

After Axelle learned all the methods to destroy the invisible space and time tunnel between the two worlds, he also started to develop a kind of sensitivity to detect the location of that tunnel. 

His judgment said the tunnel was in this headquarters, somewhere inside the void. 

However, the specific area was not at this simple prison, anyway. 

It should be on the other places, which was located on a higher floor than the prison. 

Axelle was detained in a simple-looking prison, and the prison was built underground, right below the headquarters. 

People called the prison a dungeon, and there were many other prisoners inside. 

Of course, Axelle had a 'VIP' treatment, so he didn't see other prisoners when he was detained. 

The prison looked simple, like the usual old prison, but it was actually full of magic and high-tech features.