Shu, a dropout from the school for the brave who has never improved in either swordsmanship or magic, is finally advised to expel from the school by the school principal!Two beautiful witches suddenly appear in front of Shu, and in fact, Shu is the chosen one who has inherited the soul of the Demon King, and in order to manifest her great power, she needs the cooperation of these six witches. That's what she is told.Shu, who immediately received instructions on how to free her, was able to shoot magic for the first time in her life, and successfully passed her final exam, which had caused her to be expelled!!And as a prerequisite for Shu to become the Demon King that the witches desire, she first decides to become a hero with the power of the Demon King.The Boy Demon King's School Musou Fantasy begins!!!