Bisco is gravely wounded by the shot from Kurokawa. Milo leaves him behind to storm into enemy territory and rescue his captured friends, Pawoo and Jabi, but Kurokawa awaits with meticulously set traps. During their confrontation Kurokawa reveals his great ambition and the secret behind the Mushroom Keeper's persecution.

Milo is left standing at death's door by Kurokawa's traps. Kurokawa has once again captured Jabi, and this time he shares a glimpse of his terrifying plan to utilize Tetsujin, the very same defensive weapon that covered all of Japan in the Rust Wind. It seems like no one can stop Kurokawa, and yet at the very moment Jabi feels that despair, a familiar face appears before Kurokawa...

Bisco falls into Tetsujin's reactor, taking Kurokawa down with him. The reactor begins to overload, with Milo and the others just barely escaping in time as the dome starts to collapse. However, they're given no time to grieve their loss of Bisco before their next trial assails them. With Bisco gone, Milo tries to figure out what he can do on his own now.

Tetsujin is heading for Imihama, repeatedly attacking Milo in a fierce assault. Yet just as he's about to be killed, Bisco revives from within Tetsujin. Together Bisco and Milo join forces in the final battle against Tetsujin!