Kurogane Yaiba is a boy who aspires to be a samurai instead of following the ordinary path of a regular child. He undergoes rigorous training with his father, living only in the forest. One day he is sent to Japan, where he must confront a completely new civilized reality. There he encounters the Mine family, the evil Onimaru, and even the legendary Musashi, embarking on numerous dangerous adventures that make him stronger each day.