"psychopath" "monster"? Erm, he was a child who came from an abusive home, and this resulted in him having a range of mental health problems which went unnoticed and untreated. His brothers death was accidental, and his knife murders a tragedy. Yoseob never understood love, he was never shown this as a young child so developed attachment issues to his cousin, he's now in hospital, not sure why you want him to be murdered too, what would that achieve ?
Well, at least to me, I think that would have prevented his murdering of the eight people, had he been dead. And even though he's in the hospital, his condition hasn't improved anyway. I'm surprised he wasn't sentenced the death penalty.
Watashi daijoubu :")
Hm. Despite the fact that Yoseob was raised in a bad way, that doesn't excuse the fact that he committed a crime. We shouldn't be giving him pity.
All in all, I think everything would've been fine if they just killed him. You can't control and change a monster which you created, in the end, you created that psychopathic monster and the only way to end it permanently is to kill him.
It would count as self defense since he was the first who harmed the other.