Shadow is a boy who builds a glider to fly medicine up a mountain.
Shadow used to herd goats with his family atop the mountain. A year ago the only path up the mountain collapsed during a storm. At the same time some of their goats fell ill and died; they couldn't get medicine up the mountain because of the collapsed path. Shadow later went down the mountain to find another means of transporting medicine.
Shadow tests his unmanned glider, and heads to the crash site to find it had hit Cooro. He explains to Cooro what he was doing, and Cooro is so impressed that he offers to help fix the glider; Shadow gives him cheese in exchange.
The next day, a storm comes in and Shadow insists on trialling the repaired glider. Shadow pilots while Cooro mans the reel from the ground. The rope snaps so Cooro flies up to guide Shadow in for a safe landing. Upon learning the Cooro is a +Anima, Shadow feels betrayed and pathetic, so orders Cooro to leave.
Someone calls Shadow to the doctor's house where his father is waiting. He explains that a fever has broken out on the mountain, but the path has collapsed so they can't get medicine up there. After seeing the collapsed path for himself, Shadow heads back to his glider. While flying, Shadow struggles to control the glider. Cooro lands on the glider and instructs Shadow how to fly; they make it to the mountain farm safely with the medicine. Cooro quickly falls asleep, exhausted, and when he wakes up Shadow gives him some more cheese.