The 4th Wall was the polar opposite of the Reforming Wall. Where the Reforming Wall focused on defense by blocking everything, the 4th Wall focused on attack by destroying everything. If one came close to it, one would instantly die. The 4th Wall may seem stronger than the Reforming Wall, but if one used both spells on the battlefield, the 4th Wall would destroy and the Reforming Wall would block. No one would win. That's why there was no reason to use it here. Or was there? You see, the reason the Reforming Wall was called the Reforming Wall was due to the fact that if one broke the Reforming Wall, it would form again. It was easy to break the Reforming Wall, but you couldn't use any kind of Magic. You had to use sheer physical force. But if one broke the Reforming Wall and then used the 4th Wall while there was no Reforming Wall, the Reforming Wall wouldn't reform. Since the 4th Wall was a spell made by Kagutsuchi he could cancel the spell and escape the effects of the Reforming Wall. But he'd have to be fast to activate the 4th Wall again before the Reforming Wall reformed.
Now that Kagutsuchi was inside where the Reformin Wall once was and where the 4th Wall is now, his castle stood in front of him. And what a majestic castle it was. There were 4 golden pillars situated around the red palace, guarding it. The main body of the palace was a flat cube, excluding the top of it which was pointed up like an ice cream cone. The pure white steps leading up to the main door were made from pure Divine Magic. Kagutsuchi entered the place, oblivious to what was inside it.