This is just another self insert "Bad things always happen to good guys" I bet the author of this was a loser and wanted to write something where a loser becomes overpowered and kills all h that have wronged him. When Mimori's backstory is revealed and he had an abusive child hood, that was the author self insert of what he had wish had happened to him so he had a valid reason for being a loser because realistically that never happened. There's a scene where his "inner demon" is telling him to stop pretending to smile and let your true self come out, that was one of the corniest, cringiest scenes I have ever scene. I bet later down the line theres gonna be a harem, which is a classic for these self insert losers. Don't watch this garbage.