After escaping Imihama together, Milo and Bisco trudge out into the desert in search of the Rust-Eater Mushroom, hoping to find it before Pawoo and Jabi succumb to the rusting disease. Eventually they come across Bisco's crab Actagawa, which hid during the events in Imihama. Milo struggles to ride the giant crab, but he finally manages to control it. Later, the pair stop by an old abandoned gun emplacement at Nikko Senjogahara to rest and inside they find Tirol struggling to breathe. Milo quickly saves her from a "balloonworm" that Kurokawa secretly planted inside her which expands without regular doses of an inhibitor...