And Spiritual Academy too, Kimura Kazuki thought to himself.
It was important to note that one's memories were engraved in the depths of one's soul, while the brain only functioned as storage space. The answer as to why someone who suffered a concussion and amnesia could retrieve their memories back was because they had not damaged their soul during the event.
It was also the reason why people who died and turned into spirits were able to keep their memories intact. On the other hand, those who turned into demons were bothered by negative emotions, and as such, parts of their soul would remain within their corpse, making them lose the memories they had of their past life. These demons would only be able to recall their memories with continuous and fruitful practice, and even so, their recollection would only be in part while their characters would change dramatically.