
Is this the prequel of that murderous school teacher? Fun

Koakuma Kyoushi Psycho
There's two version, Japanese and Korean (for some reason). The Korean was left untranslated.
I personally prefer the Japanese version because it's more... Humorous? Even though the arts wasn't the best. The Korean version was more generic (the normal manhwa aesthetic ) to me, so it didn't pick my interest much.
This prequel also have a different artist than then sequel. If you've read the first doku mushi and that other murderous school girl manga (I completely forgot the title, but one of the cover have one short haired glasses girl holding a chainsaw is what I remembered) you'll see the same artist style.
WAUUUGHHHHHH