Ordinary high school student Mamoru Shiraishi harbors a secret: he remembers his past life. In another world, he was a hero who saved humanity from the brink of destruction. But that was a lifetime ago. Now, he’s just an average student, living a quiet, unremarkable life—or so he thought. His mundane days take a dramatic turn with the arrival of a new transfer student, Mai Shiina, who boldly declares: "I can’t live without you!" As the past collides with the present, Mamoru finds himself caught between the memories of his heroic deeds and the unexpected complications of a blossoming romance. Together with Mai and a cast of quirky classmates, Mamoru navigates the highs and lows of adolescence while trying to keep his secret safe. A story of a former hero and a stubbornly honest girl, this romantic comedy explores love, identity, and the hilariously awkward struggles of youth!