In the series finale, Nature Cat and his pals realize they've come to the end of their Nature Curiosity List. Meanwhile, Sir. Galahad gives himself the title of King and moves into a barren castle and steals pieces of nature to make his castle look more beautiful.

We don't have an overview translated in English.

Nature Cat, having realized his and other cats' favorite toys have gone missing, goes on a mission to retrieve them from Bad Dog Bart. Along the way, they meet a tough pirate named One Eared Winnie, who also is trying to find the treasure. Fortunately, One Eared Winnie later turns out to be Nature Cat's long lost sister, Gwendolyn, who he reunites with.

When Hal's favorite squeaky toy Mr. Chewinsky gets lost from the dog and toy anniversary party, Nature Cat and the rest of his team find reinforcements, in Nature Dog and Houston's cousin Sputnik from Russia, to retrieve him and remove trash from the ocean along the way to save it and its inhabitants.