I, the Undead Monarch, Was Summoned by the School Belle at the Beginning

My name is Qiye, the king of the plane of the dead. I sit high on the throne of bones and walk between life and death. I have killed thousands of demons and monsters with one finger, and I have also made immortals and Buddhas bow their heads in fear. I am so strong that I have no rivals, but the dullness of life makes me tired. Until one day, a strange girl suddenly summoned me...