Pluto is a dog that bears a vague resemblance to a blood hound, particularly in his long, black, droopy ears. He has short, yellow fur and large, close-set eyes. He has three toes on each paw. Pluto's long tail is very thin and black, more closely resembling his master Mickey's tail than that of a dog. He is wearing a loose, green collar.
Pluto has a minor, yet notable role in Kingdom Hearts. He is found by Donald in the throne room of Disney Castle with a letter from the King who has gone missing. Pluto later sleeps during the conversation of options between Queen Minnie, Donald, Goofy, Daisy Duck, and Jiminy Cricket. Donald, Goofy, and Jiminy are sent to locate the King and the Keyblade Wielder. Pluto hops into the Gummi Ship at the last moment as it departs.
In Traverse Town, the group witnesses the disappearance of a star and rush off to find Leon. Pluto wanders off into an alleyway, discovering an unconscious Sora. The dog wakes him up with a lick and a sudden shove. Sora asks Pluto where they are, but the dog seems to hear something and rushes off. He disappears for the remainder of the game, although it's possible he was reunited with King Mickey, as he appears suddenly at the end-credits scene carrying a letter with the King's seal. Sora, Donald, and Goofy chase him over the hills.
Pluto has a brief appearance in Kingdom Hearts: Chain of Memories at the beginning. Sora, Donald, and Goofy spot that he is carrying an envelope with the King's seal. Pluto rushes off, the three running after him. However, it appears they lost track of him or gave up due to it being night. However, the pursuit of Pluto leads the trio to a crossroad which eventually leads to Castle Oblivion, where the events of the game take place.
Pluto returns in Kingdom Hearts II, oddly in The World That Never Was, apparently tracking Axel for unknown reasons. He follows Axel into an alley only to lose him once he enters a Corridor of Darkness, but then Riku, who is wearing a Black Coat, appears and opens another Corridor of Darkness for him. Pluto arrives on the Destiny Islands just in time to prevent Kairi from going with Axel. Pluto and Kairi escape into Twilight Town where they meet Hayner, Pence, and Olette. Axel soon appears and kidnaps Kairi, and Pluto chases after them.
Pluto and Kairi end up imprisoned in a cell in the Castle That Never Was. They are rescued by Naminé and escape. They are soon confronted by Saïx, but Riku appears in his disguise as Ansem and chases him off. As Riku is about to leave, Pluto blocks his path and moves Riku in the direction of Kairi. Riku allows Kairi to remove his hood. Pluto disappears until the defeat of Xemnas, leaping into a corridor made by Naminé which leads to the Destiny Islands.
Despite the fact that Kairi, Donald, Goofy, King Mickey, and Pluto passed through the portal to the islands, Pluto was not shown when Sora and Riku returned. Pluto is seen in the credits with Huey, Dewey, and Louie, Scrooge McDuck, Donald, Goofy, and King Mickey when they return to Disney Castle.
In Kingdom Hearts II, Pluto apparently takes a liking to Kairi, as he spends most of his time with her, does not hesitate to follow Axel as he escapes with her, and attempts to comfort her when they are locked in the Castle's basement.
Pluto first appeared in Episode 2 when Sora fixes Traverse Town's Bug Blox Corruption, and the Journal shows everyone in Disney Castle's computer the message, "Their torment has been lessened" and a scene is shown, from the first game, where Sora, Donald, and Goofy first meet. The scene shifts to show Pluto in the background running into a Corridor of Darkness.
- The contents of the letter in Pluto's mouth at the end of Kingdom Hearts and beginning of Kingdom Hearts: Chain of Memories are still unknown, without it even being addressed in Kingdom Hearts II (though because of the year of sleep, Sora and the others may have forgotten about Pluto's message).
- In the Kingdom hearts 358/2 Days Manga, he is sent by Riku to infiltrate the Organization's castle; Xion "adopts" him during a mission in Twilight Town, but he soon leaves into Dark City to meet Riku.