Pikachu, Clefairy, and Jigglypuff are playing in a field of flowers when suddenly, a boy in a ninja suit falls from a nearby tree. He is then reprimanded by a Ditto for his lack of technique. Ditto introduces itself to the three, and the boy explains that he is Ditto's apprentice, a ninja-in-training named Walnut. Interested in learning more about being a ninja, Jigglypuff asks to be trained, too.
Walnut tells the Pokémon that he wants to follow in the footsteps of Koga, who he greatly admires. He also reveals that he is interested in the many different colors of ninja outfits there are, showing Pikachu and Clefairy his bag of clothes. Ditto hits Walnut with its fan for prioritizing fashion over ninja training, prompting Pikachu and Clefairy to ask what ninjas are. Walnut proceeds to show off some ninja skills, such as flame-throwing, making shadow-selves, and using throwing stars. While Walnut performs these skills rather lamely, Jigglypuff pulls them off flawlessly.
When Walnut runs over to collect his throwing stars, he inadvertently gets caught in a net he had set the day before. Ditto prepares to cut him down, but is suddenly grabbed by a Pinsir. Walnut escapes and tries to pry open Pinsir's pincers with Pikachu, Clefairy, and Jigglypuff, but their efforts are futile. When Walnut begins to lose hope, Ditto instructs him to calm down and think.
Walnut takes a long pause to formulate a plan. Realizing that Pinsir are attracted to the color green, Walnut heads for his clothes bag. After changing into a green ninja suit, Walnut waves to get Pinsir's attention. Pinsir drops Ditto, then charges for Walnut and grabs him in its pincers. Ditto then uses its flame-throwing ninja skill at the two, knocking out Pinsir and freeing Walnut.
With Pinsir incapacitated, Ditto goes up to Walnut and praises him for his efforts. Delighted, Walnut changes out of his charred clothes and into a red ninja suit, but this attracts the attention of a nearby Electabuzz, who charges for him. Walnut yells to Ditto for help, but it is now focused on recruiting Jigglypuff to become a ninja.
