After Reincarnation, I'll become the Demon King!? But it was a world where the Brave Reigned

The demons lost their hegemony over this world after the demon king was subdued by the hero.
Oppressed by humans and on the brink of extinction, they summon another demon lord, the demon lord's counterpart. That is However, he was reincarnated with the memories of his previous life still intactHe was a former human...