Yuusha wa Kosokuihan ni Narimasu ka?

Overview

The hero August challenged the Demon King to save the world from destruction but was annihilated along with his friends. In modern Japan, a kindergarten child suddenly regains his memories of his past life as the hero August. As a shadow that resembles the demon king creeps into his life, he decides to train as a 'hero' again to prepare for emergencies. In order to overthrow the demon king, he establishes the "hero club" in high school and tries to gather together his reincarnated friends from the other world. An everyday battle comedy involving a former hero who goes to high school!

Source: AniList