At the Ninjutsu Academy, Doi teaches young ninjas known as “Nintama.” One day, he goes out for a battle against a ninja from the rival clan, but vanishes without a trace. The Nintamas worry for Doi’s safety, especially Kirimaru, a war orphan who lives with him. At the same time, the Academy receives troubling news that their rivals at Dokutake Castle may be scheming something. The older ninjas infiltrate the castle to investigate, but they are stopped by Tenki, whose face is identical to Doi.