The swift and violent "mushroom guardian" Akaboshi Bisco travels through the "rust wind" that can corrode everything and threaten human death. In order to save his master, he embarks on a journey to find the magical mushroom "rust-eating". Bisco and his partner, the beautiful young doctor Milu, plunge into a turbulent adventure. They travel through the vast Saitama Iron Desert, towns built from the wreckage of defense weapons that destroyed civilization, and abandoned underground railway lines occupied by giant octopuses. All the threats they face on the harsh road are pierced through by Milu's inspiration and Bisco's sure-hit mushroom arrows! But ahead of the journey, there is a conspiracy of the evil county governor waiting for them. The stormy adventure drama that will win the "Silver Award" of the 24th Dengeki Novel Award begins!