After sealing the Keyhole of Agrabah, Sora and company continue forwards on their Gummi ship. However, en route, they come across a gigantic whale that Jiminy recognizes as Monstro, which is so massive it swallows the ship whole.
Sora experiences a flashback of himself and Riku when they were kids. In it, Sora believes that there is a monster in the Secret Place, and convinces Riku to venture together to find it. Much to their disappointment, there is no monster, but as Sora tells Riku of a girl who washed up on the islands (Kairi), Riku notices something suspicious about the door in the Secret Place.
Back in the present, Sora comes to and discovers the group inside Monstro's mouth. They come across Pinocchio, whom they had encountered in Traverse Town and soon escapes with a Gummi piece. They also meet Pinocchio's creator, Geppetto, but Pinocchio notices another figure lurking around and follows.
Sora and company take pursuit, realizing that this figure is Riku himself. Riku abducts Pinocchio, challenging Sora to find them to gain information about Kairi. As the trio follow, Riku rendezvouses with Maleficent, who reminds him not to dabble in the darkness too much. When Sora catches up with Riku, the two fight, but Pinocchio is captured by a Heartless known as the Parasite Cage. Though the trio, with Riku's help, manages to defeat the Heartless, Riku disappears again.
Back on Geppetto's ship, the trio once again realizes that Riku has taken Pinocchio, intending on using his heart for Kairi before questioning Sora's determination. They eventually corner him inside Monstro's stomach, where Riku attempts to have Sora join him. But Sora disagrees, believing that Pinocchio, despite lacking a heart, does have a conscience. Riku makes a getaway as the Parasite Cage once again reappears.
After a struggle, Sora and company slay the Parasite Cage. The chaos, however, is so much that Monstro sneezes the group out. Meanwhile, Maleficent explains that Riku needs to go into Kingdom Hearts in order to restore Kairi and grants him control of the Heartless...
Tropes:
- Adaptational Expansion: In Pinocchio, we only ever see Monstro's mouth. Here, we see the rest of his innards, and it is... bizarre, to say the least.
- Developer's Foresight: Since Monstro isn't exactly a full world and technically doesn't have a Keyhole, you can simply get to the Save Point at Geppetto's boat and immediately skedaddle out of Monstro. But if you decide to come back and participate in both fights against the Parasite Cage after clearing Hollow Bastion, Riku won't join Sora for the first bout, and will be possessed by Ansem and speak creepily in the second bout.
- Wham Episode: This is when Sora catches on that Riku is with Maleficent.
- Womb Level: Mostly.
