On their way to Akita, Bisco and Milo pass by the sea of Calbero and arrive at a desolate town under threat from the deadly creatures, Flying Blowfish. A town that's also full of children and devoid of adults. Meanwhile, Pawoo encounters a mysterious couple living in some ruins as she pursues the others.

With the information obtained from Tetsujin Town, Bisco and Milo continue to head north. As they make their way through Shimobuki Prefecture, the land encased in snow, they encounter Tirol, nearly frozen to death. With Tirol's aid, the two continue their journey toward their final destination - Konakidani, the land said to contain the Rust Eater.

Bisco and Milo finally reach Konakidani when the Pipe Snake, a divine beast with two heads that's the size of a dragon, appears before them. That's also when Pawoo catches up to them with the worst possible timing. Soon enough, even Pawoo is dragged into the intense battle against the Pipe Snake. Meanwhile, Kurokawa also closes in around them...