description is that hero was getting minimum wage and working overtime? and demon king or queen I don't remember demon king or queen want to hired hero to come work for her,him and offer more salary and hero accepted it immediately I think? sorry for bad grammar and english
Sound about right... The OP description is kinda a mix of the two.... Or could be something different entirely... there are so many of those ... hero joins the maou stories the manga Yamemasu Tsugi No Shokuba Ha Mao Jo, vaguely matches as well...