Kaiman is the main character of the Dorohedoro series
Kaiman is the main character and appears to have been the victim of a transformation. This left him with a lizard head while the rest of the body is human, and having no recollection of the past, besides that he is now immune to magic and can regenerate pretty fast.
He lives in the Hole with Nikaido who found him and cooks Gyoza (his favourite food) for him. With Nikaido they try to find the man who did this to him .