Rotts

Rotts is Yuki's best friend since childhood, their relationship founded on the shared interest of building aircraft. Though he's baffled by Yuki's reckless strategy of improvization, the two form a good team, and Rotts is the one always there to see his friend to the mainland—and lift him off the ground whenever he falls.

Story
When their 19th plane, the best model yet, has been completed and has been prepared for take-off, Rotts promises he will meet Yuki on the mainland one day. It takes nearly the full span of Yuki's adventure passing first, but they finally meet in Raflid Town. Yuki has lost his dear friend Alfina (whom Rotts hasn't met yet), and, with yet another crashed plane (this one a refurbished model from legendary air pilot Schmidt), is directionless. Rotts has been working at the workshop with Schmidt for a long while, but with the flight units all broken thanks to Xorn's growing power over the world, he and his superior are both just as somber.

Still, Yuki remains perseverant, even through Schmidt insisting that there was no hope to take to the skies and rescue Alfina. Rotts is hit worse than this, perhaps, than his friend. When Yuki insists the two have to do something, Rotts laments, "If Schmidt can't do anything, no one can."

It's Yuki's turn to be the friend Rotts always had been for him.

Both distraught by the situation, the two boys get into a scruff, eventually toppling the pile of logs they are balancing upon. Lying at the collapsed base, they watch a bird glide across the sky. The duo stand up, brought back to their roots; in chorus: "A glider!"

Yuki crashes it.

He limps back to the town, repeating over to himself that he'll get airborne again, even if it's the last thing he does. He's delirious with exhaustion when Rotts and Ulf greet him; when Yuki passes out, Rotts takes Yuki back to the inn when he passes out, while Ulf and Yuki's other friends pay Schmidt a visit. It's the legendary pilot who greets Yuki when he comes to, and with his hope revitalized by that fleeting chance at flight, he follows Schmidt's guidance and recovers the old Crystal Rose, the plane that won Schmidt countless competitions and was never powered by a flight unit.

Already a seasoned workshop team, Rotts and Schmidt restore the Crystal Rose, and for one final time, Rotts bids Yuki farewell, sending him, his friends, and Schmidt into the sky and through the depths of Xorn's roots.