Series by 有馬レンジ

Yū Amanogawa, a high school student and reincarnated hero named August, regains memories of his past life as a warrior who failed to defeat a world-destroying demon king. As a kindergartner, he learns the demon king plans to reincarnate in modern Japan, prompting him to train as a hero while living an ordinary life. In high school, Yū forms the "Hero Club" to reunite his former comrades, starting with his familiar Pal, a small creature who joins him. The group faces an early challenge when a reincarnated monster, posing as a school senior, attacks Yū, testing their skills in a chaotic clash. Balancing school life and hero duties, Yū’s efforts blend everyday antics with bursts of action as he prepares for the demon king’s return.