The Fallen Hero And The Rikka Witches summary:

Shuu, a dropout at the Academy for the Brave, whose swordsmanship and magic skills have not developed, is finally advised by the headmaster to leave the academy!Two beautiful witches suddenly appear before him and tell that he is the chosen one who has inherited the soul of the Demon King and that he needs to cooperate with the witches to unleash its mighty power.Shuu quickly learns how to liberate himself, and for the first time in his life, he is able to use magic and successfully clears the final examinations that will prevent to be expelled from the academy! Shuu then decides to first become a hero with the power of the Demon King as a prerequisite for becoming the Demon King that the witches want--.The boy demon king's school warrior fantasy begins!