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. The cause of this catastrophic state? Mushroom spores. At least, that's what everyone thinks. Enter Akaboshi Bisco. He's known as the "Man-Eating Mushroom," and is a wanted archer whose deadly aim instantly sprouts mushrooms wherever they land. However, in truth, he's a "Mushroom Keeper," committed to spreading fungi to enrich the land and return it to its former state.

A young girl—Chloe La Forêt—is alone and unconscious in the Corpse Forest. Well, it's too bad. At least the monsters will finish her off within a few days. Except this girl gets rescued in the nick of time. And the man who finds her? He's her new boss, Alchemist Kurakazu Rintarou. Chloe has a knack for cleaning and thus becomes his housekeeper. But she quickly reveals another hidden talent of hers—necromancy! Watch as this story of science and fiction unfold under one roof.