I Summoned The Hero, To The Present Age

I Summoned The Hero, To The Present Age summary:

The black history notebook of my middle school days was sent from my parents’ home. While being nostalgic, as if I had made a proper magic square, I summoned the Hero from another world. “–Who are you, an underling of the Demon King?” A story of struggling to return the hero who was summoned by mistake by a 25-year-old OL who should have completely cured her chuunibyou disease.