Mawangeul Geumandun Iyu

Demiurgos DCLXVI, or Deus, is the 666th resurrection of the Demon King, fated to battle a warrior of the Pure Blood clan every 100 years to liberate his fellow demons from hell. But instead of waiting, Deus escapes 20 years early to forge a new identity among the humans.

(Source: WEBTOON)