The narrative reaches its crisis when a catastrophic wildfire engulfs the suburban forest surrounding Iris's home. Although Arco's time crystal is recovered, the children are trapped in the blazing inferno. Mikki braves the firestorm carrying Iris, Arco, and baby Peter. When flaming debris collapses around them, Mikki shields the children with its own chassis, sustaining fatal structural damage.
Trapped in an underground cavern with depleted power cells, Mikki spends its final mechanical energy carving murals onto the rock wall, depicting memories of the children and a radiant drawing of Arco and Iris soaring across a rainbow. Mikki permanently powers down just before Iris awakens, leaving its love and memories immortalized in stone.
As rain clears the air, Arco uses the crystal and morning sunlight to activate his suit, bidding Iris an emotional farewell before launching into the sky to create the rainbow that returns him to 2932. The film's final montage reveals that Iris reunites with her parents—who recommit to physical presence—and grows up to become a visionary architect. Her career-defining blueprints for floating cloud canopies are revealed to be the exact prototypes for the sky arboretums where Arco's family lives eight centuries later, completing an unbroken, 857-year temporal loop of mutual salvation.