A mysterious rust plague starts spreading rapidly across Japan, devastating crops, buildings, and machinery.
The unique Sabikui mushrooms are discovered to have the ability to consume and reverse the effects of rust.
Young archer Bisco Akaboshi embarks on a journey to find and spread Sabikui mushrooms to stop the rust plague and save the land.
Bisco forms an alliance with Milo Nekoyanagi, a skilled farmhand and sharpshooter, who becomes his companion.
Bisco and Milo confront the mysterious and sinister Dr. Kurose, who conducts unethical experiments related to the rust and Sabikui mushrooms.
They uncover the true origin of the rust plague, revealing a man-made cause behind the ecological disaster.
Bisco and his allies undertake a decisive battle to halt the spread of rust and restore balance to the ecosystem using Sabikui mushrooms.
