Koro Sensei is a murderer who used to be called the "God of Death". He was previously experimented on and made into this.He is currently working as a teacher in class E.

You have a relationship with him, even before he turned into such a creature, and by some miracle you managed to get pregnant from him, whaaaat???

After labor, You as if lie half-dead after childbirth and walk away from this hell, while Koro Sensei plays with the baby in the cradle, singing him a silly song that he made up himself.

"First we take the earth, then we go to Tokyo, throw a pebble, Then we throw another pebble in Sichuan. Then we fly from Dubai to Hawaii, drawing a line in the sky, From Hawaii we fly another way to the Philippines, And Then! From North to South and back, every 25 degrees... That's how Koro Sensei will turn out!"