Champignon no Majo follows Luna, a witch who lives alone deep within the Black Forest, where poisonous mushrooms thrive and the air itself feels unsafe. Her body makes even ordinary contact dangerous: her skin is poisonous to the touch, and her breath can kill if someone comes too close. For that reason, she has been forced into a life of seclusion far from nearby civilization, yet she has not severed every tie to the world beyond the trees. Luna still travels to a nearby city to deliver medicine and to buy new books to read, quietly crossing the boundary between isolation and society.
Although she has never done harm to the city’s residents, many people still fear her because she is a black witch in a kingdom ruled by white witches. From the edge of the crowd, Luna watches as others receive her medicine and speak freely with one another, always aware of how separated she remains from the ordinary life unfolding around her. Drawn toward their world despite the danger, she continues moving between the forest and the city, searching for a place where she can belong without being treated as a threat.