Japan has collapsed after the Great Disaster. Kiruko accepts a request to take a boy named Maru to a place called Heaven. Meanwhile, children live behind the walls of a nursery in luscious green surroundings. After receiving a mysterious message, Tokio begins to doubt the world around him.

Maru and Kiruko return to Tokyo to find a neighborhood crowded with tents. When Maru goes off to a game center, Kiruko is left to gather information for herself, and hears a scary rumor.

Maru and Kiruko decide to head to the Ibaraki facility of the Takahara Academy. Since it's on the way, they agree to help Juichi confirm whether his baby is still alive. Arriving at the Walled Town, the situation is very different to what was expected.

Mimihime, Shiro, Anzu and Taka all head outside through a hole in the wall, as they search for an answer to their teacher's test. Meanwhile, Kiruko is in tears after Robin does something terrible.