The children search for clues about the missing Okada and arrive at an attraction that suddenly appears in Uropia called "Okada Castle". There, they find themselves re-experiencing attractions they had previously beaten! As the story reaches its climax, will the children and Okada be able to escape "together"...!?
The children somehow manage to return from the lab where the secrets of Uropia are hidden. There's a glimmer of hope that they might be able to reclaim their lost friends, but Okada remains missing. The mysterious girl tells them that Okada Yu "re-entered" Uropia in his last attempt, and they make the decision to bring him back. They finally find him in the huge, pitch-black Okada Castle that suddenly appeared in Uropia. As they storm inside, they're faced with attractions they had previously beat. The children must test the new selves they've discovered through the "growing pains of the heart". Confronted with the truth of Uropia, will Okada and the children be able to escape safely "together"...!?