The demon lord tamer's strongest domination

For incompetence, Lewin, a Demon-Tamer adventurer, was banished from the hero’s party. Without being acknowledged for his achievements as a commanding officer... However, the moment he comes into contact with Sasha, the Demon King of Death, one of the sealed Seven Demon Kings, he awakens to become a Demon King with the ability to subjugate Demon Kings! Moreover, by shattering the seal, he tames the demon king, Sasha Source: MU