Nagara and Rajdhani arrive in a world called "Filmmaker," and discover a movie filmed entirely from Nagara's POV. Mizuho discovers a stray dog by the name of Yamabiko, claiming to be another castaway who attended the same school as the other students.

Having learned the truth about This World, groups led by Ms. Aki and Hoshi prepare to go their separate ways. Nagara finds himself in an upside-down world he cannot freely leave, and is forced to work on building a Tower of Babel that reaches downward.

While traveling the wilderness, Mizuho asks Yamabiko how he became a dog. Yamabiko then relates how, 5000 years ago, he wandered different worlds all alone, until meeting a girl to whom he gradually opened his heart. But their happiness was short-lived.

In a vast frozen waste, twins Sou and Seiji have been fighting each other for millennia. Ms. Aki says that to change the world, they need the twins' "Reverse" power, and Nagara and Mizuho come to assist. Yamabiko questions Sakura, one of Mizuho's cats.

After learning of Nozomi's death from Kossetsu's letter, Nagara and Mizuho hold a memorial service for her. While advancing the project to return home, they are visited by an old friend, who tells them the story of when he met the man who invented death.

Nagara attends the opening ceremony of his technical school, but feels out of place. He sees Mizuho leaving her all-girls' school, but she brushes him off. He recalls what happened after blasting off into space, questioning if he ever really went adrift.