OVA bundled with the special edition of the manga's side story.

A plague-like wind blows across the arid, sandy expanse of a post-apocalyptic Japan. As it sweeps over the living and nonliving alike, rust is all that remains in its wake. The cause of the catastrophic state of the world is believed to be mushroom spores. Bisco Akaboshi, known as the "Man-Eating Mushroom," is a wanted criminal archer whose arrows instantly grow mushrooms wherever they land. However, he is in truth a "Mushroom Protector," a person who spreads fungi in order to enrich the land and return it to its previous state. Alongside the crab Akutagawa and young doctor Milo Nekoyanagi, Bisco ventures through the wastelands of Japan searching for the legendary "Sabikui"—a panacean mushroom said to devour all forms of rust.

When Dr. Eggman (Robotnik in the US version) holds the president and his daughter hostage, Sonic must comply to the evil scientist's demand of going to Eggmanland to stop Black Eggman and deactivate the city's generator before it reaches critical mass. Little does Sonic know that it's a trap to activate Hyper Metal Sonic, a robot counterpart built by Eggman to destroy our hero. (Source: ANN)

After he witnesses his father's murder at the family dojo, Hazuki Ryou dedicates his life to finding the man responsible—a mission that takes him from the streets of Yokosuka, Japan to the sprawling metropolis of Hong Kong, and beyond. Soon he will learn that larger, mystical forces are at play as he trains to become the ultimate martial artist in his quest for revenge.