The Demon Queen Summoned the Wrong Guy and Made Him Her Butler – intro video

A magic circle summons you to another world, and when you open your eyes you're kneeling before the throne of the Demon Queen's castle. The Demon Queen says the summoning went wrong, she got the wrong person, and she can't send you back for a year. Then she clears her throat and announces your new position. “From today, you are my personal butler. …N-not because I need you!”