What happened when Arakune transformed

A year ago, Litchi had left Sector Seven, where she’d worked alongside Kokonoe and Tager, to help someone. That person had been researching seithr and the Boundary, which was said to have brought this substance into the world. But then, something happened to him. He became increasingly confused, eventually disappearing from public view, and finally, he ceased to be human.

It was the result of his continued exposure to seithr and his overzealous research into the Boundary. He became unable to distinguish himself from the Boundary, and lost his original form.

Just as it is impossible to restore something that has been digested back to its original state, it is also impossible to return something that has been assimilated into the Boundary back to its previous form.
- Blazblue: Calamity Trigger Part 1 Chapter 2