The Professor was a well built man, he had black hair and a beard, he wore glasses to help his sight, he smoked when under stress.
He was a loving father, however his fusion with the demon caused him to battle with his humanity, eventually dying as a Devilman in order to stop himself from giving in to his demon half.
After discovering the strange demonic mask whilst on an expedition and trying it on he gets possessed by a demon and and forces him to kill Ryo's dog John. When Ryo confronts him he laughs and locks him out of his study. Then late one night he attempts to kill Ryo when he was sleeping however Ryo blocks his attack. Briefly regaining control of his actions he runs away and locks himself in his study before setting himself on fire to free him from the demons control.