Rantarō, Shinbei and Kirimaru are ninja apprentices in the Ninja Gakuen, where first grade ones are called "Nintamas". They must learn everything a ninja must know, but as for our heroes, money, food or playing are more interesting. The series show the everyday adventures of our heroes.

Mahito Tsujimuraas Headmaster
Minami Takayamaas Rantarō Inadera
Mayumi Tanakaas Kirimaru Settsuno
Chikao Ohtsukaas Denzo Yamada
Teiyu Ichiryusaias Shinbei Fukutomi
Toshihiko Sekias Hansuke Doi
Mami Matsuias Shōzaemon Kuroki
Chie Satoas Isuke Ninokuruwa
Kumiko Watanabeas Kingo Minamoto
Tomiko Suzukias Kisanta Yamamura