The Demon King and the Hero Have Become Outdated

Igusa, a young man fascinated by evil, is reincarnated as the Demon Lord he has long admired, but the world he enters is in trouble. An interstellar war has left the planet devastated, and both swords and magic have fallen into decline. The world he was meant to conquer is already close to collapse. A girl who calls herself a Hero and a beast-eared girl from another world soon appear. Igusa recruits them into his ranks without hesitation, intent on pursuing evil despite having no land left to conquer. He sets his sights on taking over the entire universe with his new companions.