In a world torn by war among Humans, Beastmen, and Demons, a man is summoned to be the Hero who saves the realm. Completing his mission, he returns home only to face betrayal by the fearful Human King. Trapped and reborn as a baby in modern times, he grows up as Suzaki Setsu, a high school student. Despite being bullied for his bookish nature, he tirelessly seeks a way back to the other world. Eventually, he finds himself summoned once more, this time with his classmates, to a world five years ahead. Evading the Human country, he befriends the Demon King and Beast King, but trouble follows as he gets entangled in dark schemes. Follow the tale of a reluctant former hero lacking in motivation.