 They re baaaaaaack! Rocky, Colt and Tum Tum in their first adventure since their last! Now, older, and more advanced. Grandpa now tells them they re ready to learn from a teacher in Japan. But before they can go, the boys have a baseball match which really takes a turn for the worse. Also, a childhood rival of Grandpa Mori Shintaro s (Funny, wasn t his last name Tanaka in the last movie? Oh well) by the name of Koga wants revenge for a past accident, and because Grandpa has in his possession a dagger from a championship match that he felt he should ve won, so he sends his dimwitted nephew and two of his numb skulled buddies to Grandpa s house to get it. Rocky, Colt and Tum Tum meet them and really kick things up. Later on, Grandpa goes to Japan and get s in a cab accident, so the boys use "Ninjanuity" to get there and help. While in Japan, the boys make new friends and new enemies.