Black Summoner, Vol. 1 (manga)

"Fight the strong and win-if you can't do that, you're a weakling!" A boy finds himself in a strange place, with no memory of his past. His name is Kelvin, and he soon discovers that he's been transmigrated to another world, giving up even his memories in exchange for extremely powerful abilities! Thus, he begins his journey as the world's strongest Summoner-challenging one mighty adversary after the other, gathering allies, and discovering his calling as a true battle junkie!!