August, a brave man who challenged the Demon King who destroys the world, will be annihilated with his friends. By the way, in modern Japan, the courage of kindergarten children suddenly regains their memory as a hero. In front of the courage to study as a "hero" in preparation for an emergency while being amazed by his family, a shadow that seems to be a demon king creeps in ... In order to defeat the Demon King, Isamu who became a high school student established the "Brave Club" and decided to work hard to gather former friends ...? Everyday battle comedy unfolded by a former hero who goes to high school!