F-rank Vessel of the Monster king

Zareth, the ancient ruler of monsters, descended to the human world to see with his own eyes what humanity truly is. The descent succeeded—but when he awakened, he found himself living inside the body of Kael, an F-Rank instructor at the nation’s strongest Hunter academy, known as the weakest teacher alive. Now bound to this fragile human vessel, Zareth hides his identity as the power of the Monster King slowly awakens within him. And as he learns what humans are really like, the world begins to change in ways no one expected.