Hachimaru, a weak boy, is unable to run or eat hard food, making him frail. Despite his physical limitations, he harbors a desire to become a samurai. However, for a boy who struggles to survive without his father's aid, this dream appears unattainable. Nevertheless, everything changes when a samurai cat suddenly arrives in his life. This science-fiction samurai saga is a collaboration between a legendary manga creator and an up-and-coming sensation.