One of the things very early in the series is that we know how terrified people were of En. Even with him kidnapping Nikaidou when she tried to hide her sorcerer magic, it was truly difficult to gauge. But here against the root of evil that consumes Ai, it really shows. Even with the help of the Store Knife, Nikaidou in her transitioning devil form was up against a wall.
En is just terrifying in how he can use his mushrooms. Any mushroom he spreads on some can be taken apart where he can examine the field and operate remotely at a safe distance. Like we saw how he dealt with Caiman earlier in the series, the strategy holds because the mushrooms take space on the inside. Thus, at some point there is only so much room in the body that the mushrooms can be, and thus En has the evil in a check condition.
We have known for quite a while that Ai, Aikawa, and Caiman are the same being. Granted, the Caiman that came back recently is the one that died around 1 year ago. Still, there were questions of how Ai became Aikawa. Who is the thing that takes over Aikawa/Ai?
First, we have Ai’s desire to be a sorcerer. Kasukabe wasn’t willing to operate on him until Ai jumped into the hole. We were led to assume that Ai became an Artificial Sorcerer, but that wasn’t true. As the thing that Ai jumped into was the death and hate of the humans who were killed by the sorcerers. It only makes sense that the hatred of those humans who suffered carried their will forward into Ai. The reason the Hole water aggravates the sorcerers is more so the fact that it isn’t truly rain but the hatred of those dead humans killed by the sorcerers.
Sadly, Ai got manipulated by that hatred. He had nothing left in his life, so no surprise that he wanted to be a sorcerer. The fact is he was manipulated into getting that wish. The mark of the cross-eyes resembles that of the liquid in the hole. While it was Aikawa who led the CrossEyes, he was still being manipulated. The Crosseyes were gathered to aid those who didn’t have the smoke to be sorcerers. But this band being formed is what brought out sorcerers to be hunted down. Much like Ai, the CrossEyes were pawns to this hatred.
The sad part for Ai is he let himself be used because he didn’t have much left to live for. As Aikawa, he was able to enjoy life as he became partners with Risu. Still, he lost his memories as Ai as he let the being of death influence him because he had nothing left in life. Might as well enjoy life while being influenced by the even thing. You can’t blame Ai/Aikawa here because a lack of a desire to live can just make you give up. Wanting to escape reality into your delusions.
It looks like Ai can finally rest, but that is not the case. It gets mentioned that all the sorcerers are brought in one spot. Furthermore, it seems clear that Chidaruma was the only original Devil, while the rest were sorcerers. Does that mean Chidaruma was the one who told Nikaidou to get the Store Knife? We see from Kirion that there is a door bringing a natural amount of the rain that drives fellow sorcerers crazy. Could it be possible that it is being brought into the Sorcerer’s world from the Hole?
It feels like this is all a game to Chidaruma; after all, he created Sorcerers out of clear boredom, as we are told. The only hope is the fact that Nikaidou has two usages of her time magic, but how can she even get into position to use it?