Heeseung wakes with memories that do not belong anywhere in his life now: a woman named Sena, three children whose laughter still echoes in his mind, and a version of happiness so vivid it feels impossible to have imagined. Yet no photograph, message, or person around him can explain why they feel so real. As days pass, he begins filling notebooks with fragments he's terrified of forgetting, desperate to preserve moments that seem to slip further away each time he recalls them. But the deeper he searches for answers, the more the line between memory and illusion begins to blur, leaving him caught between longing for something he cannot prove ever existed and grieving a life he may never have truly lived. A bittersweet psychological story about love, memory, and the lingering weight of lives that remain with us even after the world insists they were never there.