I'm a lackey in the underworld

I already worked myself to death under the thumb of capitalists in my last life- now I’m supposed to let some 'Goddess' squeeze the life out of me again? Saving the world? What does that have to do with me? I don't owe you a damn thing! You think you can just bully the nice guy? Fine. I’ll show you exactly why being the Demon King's lapdog isn't such a bad idea!