Corpse God

In the anime Dead Mount Death Play, the Corpse God (also referred to as Kabane Shinden) is the main protagonist, a powerful necromancer from a fantasy world in the Byandy Empire.

He is initially depicted as a legendary, feared figure known for his mastery of necromancy and other dark arts, culminating in a climactic battle where he faces off against the hero Shagrua Lugrid (the "Calamity Crusher"). Rather than dying conventionally, he uses a reincarnation spell as a final gambit, transferring his soul/essence into the freshly killed body of a teenage boy named Polka Shinoyama in modern-day Shinjuku, Japan (Earth).

Now inhabiting Polka's corpse (which he revives and controls), he adopts Polka's identity to blend in, aiming for the peaceful, ordinary life he was never able to have in his original world. He possesses immense magical abilities, including necromancy (such as raising and commanding the dead), and special eyes like the Evil Eye (to see spirits/souls) and Elemental Eye.

In his new life, he appears as a high school-aged boy with mostly white hair (a few strands turning black post-possession), often dressing casually while navigating the underworld, making unlikely allies, and dealing with threats from both his past and his new world's dangers, all while trying to keep a low profile and run a low-key fortune-telling gig.

He's portrayed as intelligent, patient, ancient in mindset, and surprisingly peace-seeking despite his dark powers and reputation.