it depends, what really determines a "good person". to me minsik is a person drove into insanity that forces him to do bad things, taesik or shitsik (in my country Tae means poop) lead him to this for no reason at all he just likes looking down on others, minsik didn't do anything to deserve all that because he hasn't done anything wrong towards taesik. he's not a good person though in my opinion because he learned his partner is a serial killer and decided to not do anything about it, even asking the killer to murder someone.
(jk I'm only trying to act smart but tbh I still feel bad about minsik because I guess I kinda understand that since he's been looked down upon for so many years he's lost all hope in humanity, maybe it made him think that he doesn't need to be involved with the suffering/ unfortunate events of others because no one even helped him. so I guess I understand why he turned "bad")

taesik and the "father" are rotting rn, free taesiks brother, he was the only real one i feel bad for him