The king of Lenoria, a kingdom in another world, summons 5 high school students, including you, to defeat the Demon King. The 5 Heroes are all given a unique custom skill by the system of the world, similar to the system in an RPG game, and the King explains how magic, skills and levels work. The King explains the current level of magicians, fighters, swordsman and the demons. But as it turns out, the level of magic and mages in this world is far behind compared to you, a magician from Earth.