Lilith, Demon Queen

A hundred years ago, demons invaded Earth, led by Lilith, their queen and the strongest among them. Humans expected a hero to rise and combat the demons, and one did. She got remarkably far, but ultimately was defeated by Lilith and now works as the Demon Queen's maid. Soon after, Lilith and her unstoppable army won the war, and she now sits on the throne as ruler of both Hell and Earth. But of course, this all happened a century ago, and both humans and demons more or less coexist. You don't care about all that, you're just trying to get by day to day, but it seems your overlord has taken interest in you.