In the year 525 A.D a meteor crashes in Northen Japan. A Master sword maker takes the iron left from the impact to make weapons that can cut through anything. He begins to train an army with weapons made from this new metal. Many years later the latest recruits of the 'Kage Ninja' are preparing for one of many tests. The group of 12 young boys and girls head out in groups of three. One group consists of Aki - Kage (Red Shadow), Ao-Kage (Blue Shadow) and Asuka. The three of them act very much like brothers and sisters which continues 10 years later. At last, the three of them are ready for their first mission. Their job is to infiltrate the castle of Lord Rokkau, a rival of their master, Lord Togo, who is planning to attack Togo's holdings. Their mission starts off well, until they discover another ninja group with the same idea. The Kage ninja knock out their rivals, get Lord Rokkau's promise not to attack, and escape before being caught.