It's a windy night with cats making noise on a full moon. Akira Masaki, who was living an ordinary life, wanders into a world where wizards and humans coexist. In this world, which is made up of five countries, a giant moon called the "Great Calamity" attacks once a year. The "Wise Wizards" have the mission to fight and push back the moon---Akira was summoned to this world as a "Sage from Another World" to lead them.