Monstro

Monstro is both a boss character and world from Kingdom Hearts. Like many of the worlds from the original game, it also appears in Kingdom Hearts: Chain of Memories. Monstro is an immense space whale that swims the Lanes Between, so large that its innards are a world to themselves, similar to Deep Space, and also appeared in the Monster of the Deep battle in Kingdom Hearts Birth by Sleep Final Mix. However, despite its monstrous size, it is actually fought as a boss in Kingdom Hearts Birth by Sleep Final Mix, in an oceanic arena seemingly based upon Pinocchio's world. Although Monstro is considered a world, it lacks a Keyhole, and its mobile nature means that Sora and his friends cannot always reach it whenever they try.

Monstro is one of the few worlds in Kingdom Hearts that do not need to be cleared to beat the game, but Gepetto and Pinocchio will not appear in Traverse Town until it is completed. Furthermore, if the player waits until they have cleared Hollow Bastion to venture through Monstro, Riku will not appear in any of the world's cutscenes or battles.

Setting
Monstro is so enormous that its playable map is bigger than that of some other worlds, like Wonderland. If one leaves Monstro and tries to go a different direction, then they will be caught by Monstro again and Monstro will appear twice on the map. Sometimes, attempting to return to Monstro will not work, as Monstro will temporarily leave his spot; Goofy will express his relief at this and the party will have to come back later. Monstro has one of the most confusing layouts of any world; it is essentially an interconnecting maze. It takes a lot of patience and a little ingenuity to make your way all the way through. Many openings open into different parts of the same room, allowing for much confusion of anyone trying to work their way through. As the surfaces in each area look the same, the only visual differences in the Chambers are the ledges, the treasures, and the occasional Barrel and debris found in them. In addition, the Chambers are marked only with numbers and are not traveled through in numerical order. Finally, Monstro defies anatomy as it is known, so natural assumptions such as going "down" to reach his stomach, for example, do not hold (you have to climb up his throat.) Sora and his party enter through Monstro: Mouth, the largest room in the world. Here, among the piles of wood and shipwrecks, the party will come across Gepetto and Pinocchio, as well as the world's Save Point. Troublesome Pinocchio leads the party down the into the whale's innards. Monstro: Chamber 1 is the arrival point for the party here. The lowest door leads to a dead-end at Monstro: Chamber 3, marked by a large piece of debris blocking off the other lowest exit. The door on the ledge of Chamber 1 will take the party to Monstro: Chamber 2, which leads to Chamber 3 going down, and to Monstro: Chamber 5 going up. Monstro: Chamber 6, which comes soon after, stands out because it is formed like a set of stairs. Chamber 5 will also send the party to Monstro: Chamber 4, from which the Monstro: Bowels and the first battle with the Parasite Cage can be found, as well as a Save Point.

Returning to the Mouth and using High Jump, given by Gepetto, the party can at last reach the Monstro: Throat, a tall, pink chamber with a series of ledges to ascend. At the top, the party can reach the Monstro: Stomach and the second boss battle against the Parasite Cage.

In Chain of Memories, there are extensions coming out of the floor which can be hit or jumped on to gain items. There are also extensions from the walls which can cause damage to Sora or Riku if approached; these can be hit to gain HP orbs.

Kingdom Hearts
Sora, Donald, and Goofy are flying away from Agrabah to get to their next destination, when they spot something huge flying towards them on the Gummi Route. They quickly realize it is a massive whale, but cannot get out of the way before the beast swallows their ship whole.

Inside Monstro's flooded mouth, the trio finds Pinocchio again and meets his father Geppetto in a broken ship. While speaking with Geppetto, Pinocchio slips off to explore Monstro. Sora and his party quickly run after the puppet into the bowels of Monstro. There, he finds Riku; the two friends exchange some quick words before Riku runs off with Pinocchio, hinting at Riku's newfound darker nature.

Sora, Donald, and Goofy chase the two through the whale, until they eventually finds them in a large circular chamber: the bowels of the beast. Pinocchio is taken captive inside the Parasite Cage Heartless. Sora and Riku team up to take down the Heartless, but are unable to completely destroy it. Riku takes Pinocchio; his words hint to Sora that there is something different about his old friend. Sora tracks the puppet to the Stomach, where Riku and the Heartless attempt to take Pinocchio's heart, but fail. Riku flees as Sora enters the belly of the beast where he defeats the Parasite Cage once and for all and rescues Pinocchio.

From all the commotion in his organs, Monstro spews out the Gummi ship and the trio to prevent any more trouble. Pinocchio and Geppetto also escape and set up a shop in Traverse Town.

Kingdom Hearts: Chain of Memories
Sora, Donald, and Goofy visit a recreation of Monstro in Castle Oblivion. There, the events of Sora's first visit to Monstro are re-enacted, minus Riku's involvement in the events that transpired. Both the chase for Pinocchio and the puppet's reunion with Jiminy are very similar. The party again fights the Parasite Cage, though only once this time. Pinocchio is told to be brave, his struggles eventually getting him out of the Heartless's maw-like belly. Sora, Donald, and Goofy also fight with several Shadow Heartless ensues in order to make Monstro spit out Pinocchio and Gepetto, as per the puppet's suggestion that a big enough struggle would cause the whale to sneeze.

Characters
Cameos:
 * Geppetto's cat, Figaro, appears inside Monstro in the Kingdom Hearts manga.

Heartless
Note: After rescuing Kairi from Hollow Bastion, Monstro will begin collecting sets of Heartless from every world except Atlantica, Hollow Bastion, and End of the World. Each time Monstro is entered at this point, it will have its normal set of Heartless, as well as the Heartless set of a different world. The auxiliary set will change each time Monstro is re-entered.

Dalmatians

 * 55, 56, & 57 - Chamber 3 on one of the mid-level ledges.
 * 73, 74, & 75 - Mouth, on the tall pile of wreckage next to Gepetto's ship.
 * 76, 77, & 78 - Chamber 3 on the highest ledge in the room.
 * 79, 80, & 81 - Chamber 5, on the high ledge.

Trivia

 * The battle which causes Monstro to spit out Pinocchio and Gepetto in Kingdom Hearts Chain of Memories is treated as a mini-game, making Monstro the only world to have a mini-game besides 100 Acre Wood.

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