Welcome to Demon School! Iruma-Kun 1 (manga)

Hopeless pushover Iruma Suzuki has found himself in a devil of a predicament… His trashy parents have sold off his soul, and he now has to live and attend school in the Netherworld. But with his unique survival skills and doting demon grandfather’s support, Iruma will surely make it through this hellish experience. He’ll just need to subjugate rival classmates, summon familiars, and more, all while never revealing that he’s human… Easy as aleph, bet, gimel, right?