In a post-apocalyptic Japan where monstrous creatures roam the land, a young boy named Maru and his fierce guardian, Kiruko, embark on a perilous journey to find a fabled paradise known as Tengoku. Maru is driven by a mysterious, personal mission, while Kiruko, a skilled fighter haunted by a past she can't fully remember, is bound by a promise to protect him. Their travels bring them face-to-face with deadly man-eaters and desperate survivors in a harsh, beautifully desolate landscape. Meanwhile, within the isolated walls of a high-tech facility, a group of bright children, including the inquisitive Tokio and the gifted Mimihime, live in sterile comfort, their every need met by robotic caretakers. As they uncover strange secrets about their own existence, the two seemingly separate worlds begin to converge in chilling and unexpected ways. Blending visceral action with a haunting, sci-fi mystery, this series explores identity, memory, and the fragile hope for a better world.