Sure, his chilhood teacher was no better than him in terms of mentality and brutality although that doesn't excuse him his own monstruous personality in present. Personnaly, i just see him as a pathetic bastard scarred by intelligent, cruel and cunning humans like Okaya and now Maria. Just hope he will die in the more miserable and painful way in two weeks, because Kinugawa is really beyond redemption after insulting memory of Kiritaka before his mother. He deserves a just retribution for his crimes.
Just hope that author don't fuck us by having Okaya and Ajiki miraculousely intervene for saving him in next chapter.