Tensei Madou Ou wa, Teihen Shoku no Kuro Majutsushi ga, Jitsu wa Saikyou Shoku da to Shitteiru

The young knight Tio was kicked out of his party by his childhood friend Aila, the hero, for not being strong enough. As he fell asleep in despair, he found out in his dream that he was the reincarnation of a black magician known as the Sorcerer King. Using his memories from his previous life, he changed his job to black magician, a "low-level job." Using a "certain method," he evolved his black magician into the "strongest job" and set out on a journey to save the world together with Iris, an elf girl known as the Sword Princess