Asta

Born without a drop of mana in a world where magic is everything, he makes up for it with a body trained to exhaustion and a five-leaf grimoire holding anti-magic swords.

Abandoned as a newborn at the Hage church alongside Yuno, Asta grows up as the one boy in the village unable to use magic — and the most stubborn of them all. The grimoire that picks him has not four leaves but five: the fifth is the devil, and inside the book lives Liebe, an anti-magic devil driven out of the Underworld's first level. His swords do not cast spells: they cut them. With the Demon-Dweller, the Demon-Slayer and the Demon-Destroyer, and later with the Zetten he learns in the Land of the Sun, Asta becomes the living answer to anyone who says a person's worth is measured in mana.