Sabikui Bisco, 1

The story unfolds in Japan, where a corrosive wind has ravaged the land. People live in fear of the rust that corrodes the cities and life itself. A boy named Bisco Akaboshi, from the scorned Guardian Mushroom tribe, embarks on a journey to find the Antioxidant Mushroom, a miraculous agent that eliminates rust and could save his dying teacher. During his travels, Bisco encounters Miro Nekoyanagi, a handsome doctor whose older sister is also afflicted by rust.