Me and My Three Grudge-Bearing Corpses

A remnant soul of a Demon God from the primordial age, waiting to transcend, and a one-of-a-kind miracle formed by the deaths of countless versions of himself across parallel worlds. Two unrelated souls are merged into one by the twists of fate. Then, through a series of schemes by the Demon God's remnant soul, he becomes one of the Three Corpses. What kind of fun will the remnant soul's will to transcend bring to the colorful myriad races of the heavens?