Maoyū Maō Yūsha (まおゆう魔王勇者, lit. Demon King and Hero), also known as Maoyu, or Archenemy and Hero in English, is a Japanese light novel series by Mamare Touno that was initially posted in a play format on the textboard 2channel in 2009. Enterbrain published five main novels in the series, in addition to three side-story novels between 2010 and 2012, selling over 450,000 copies in total. It has received several manga adaptations. A 12-episode anime adaptation by Arms aired in Japan from January 5 to March 30, 2013. The series follows the exploits of a human hero and the queen of demons who join forces to bring peace and prosperity to their war-torn world.
The story is set in a world embroiled by war between Humans and Demons. The Humans' greatest warrior known as the Hero invades the castle of the Demon King (魔王 Maō), leader of the Demons who is actually a Queen, as he is determined to vanquish her. However, instead of fighting back, the Demon Queen proposes an alliance with the Hero. She explains how a sudden end to the war can bring further chaos to the world as the Humans, once united to stand against their common enemies, would eventually begin fighting among themselves, with similar issues already occurring in the Demon Realm. Convinced by her words, the Hero joins forces with the Queen and together they execute a plan to bring prosperity and a lasting peace to both Humans and Demons alike.