He was defeated by the hero Ars during the first Human-Demon War.
In ancient times, he served as one of the Eight Great Demon Kings, close aides to the Demon God, in the Demon World.
During Laplace’s early years in the Demon World, before Laplace became a demon, Necross Lacross would beat him every time Laplace came to the human settlement.
He reunited with Laplace, who had become one of the Five Dragon Generals in the Dragon World, and worked as a diplomat to resolve conflicts in the Six-Faced World, ultimately achieving reconciliation.
In the war between Dragon World, led by the grieving Dragon God whose wife was murdered in a plot by Hitogami, and the declining Demon World, Necross Lacross, along with Kishirika Kishirisu, fled to the Human World.