Isekai Shoukan wa Nidome Desu Novel

In the world of Eclair, war rages between humans, beastmen, and demons. A hero is summoned, successfully saving the world before returning home. However, the Human King, fearing the hero's newfound power, betrays him. Transferred by magic, the hero is reborn as a baby in modern times. Sixteen years later, living as high school student Suzaki Setsu, he relentlessly seeks a way back to Eclair, despite being ostracized for his bookish nature. Suddenly, he is summoned back to Eclair by the Human country's hero summoning, this time with his classmates in tow. Unenthusiastic about another war, Setsu finds himself in a world five years ahead. He evades the Human country and reconnects with allies like the Demon King and Beast King. Despite his lack of motivation, he repeatedly gets entangled in dangerous schemes in this tale of a former hero.