Fake Hattori creates havoc (にせものは困るでござるの巻) is episode 186 of the 1981 Ninja Hattori-kun anime.Kemumaki is up to no good again - this time disguising himself as Hattori which he does many times later.
The episode starts with a child going into traffic to retrieve his ball. He nearly gets hit by a sports car, but thankfully Hattori is on the scene and rescues the child. This rescue is exaggerated and is published in the national newspaper, though we cannot thank our hero enough for saving a human's life. Kemumaki gets jealous and disguises as Hattori to play a prank. In the next scene, Kemumaki disguises as Hattori and destroys a ball with which two people were playing with. Then he bursts the balloon of a small girl in front of her mother, then he uses a shuriken and sends it into a garden, damaging its plants. The owner of the garden, an elderly man, is outraged. He and Kagechiyo the cat rendezvous later. Meanwhile, the old man, the young boys, and the mother and child are looking for Hattori. Kemumaki then leads them to the real Hattori.
Meanwhile, the real Hattori and Kenichi are out for a walk when they are cornered by the livid victims of Kemumaki. They capture the real Hattori and tie him to the branch of a tree. Kenichi, Shishimaru and Shinzo believe Hattori's innocence, but wonder who could have framed Hattori. The captive ninja then suspects Kemumaki and frees himself.
Kemumaki is still disguised as Hattori, when the real one turns up in the guise of another old man. Hattori realises that this is Kemumaki and catches him. Kemumaki tells Hattori how he was never able to be a good ninja like him. Hattori then lets Kemumaki go and returns to his trap.