Don’t Discriminate Against Species - Chapter 1 - No Degree

High school student Mikoshiba Ryouma was summoned to a different world in the middle of a war. Sensing the malice from the one who summoned him (a summoner of the O’ltormea empire), he uses his martial arts to run away, killing important people of the empire during his escape. After the escape, he rescues two twin sisters from the hands of thieves. The sisters who can use magic, swear to serve him as subordinates. Thus, Ryouma begins his journey on the path of the supreme ruler.

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

I banished the protagonist.

Shit. If only I had transmigrated a short while before.

“Did you know? I was once the most powerful person in the world, undefeatable even by the gods. If only I can retrieve my body, I could resurrect once again.”“So what?”“So... who has hidden my corpse!”