The book follows the journey of Ginko, a wandering expert known as a "Mushi Master," who investigates mysterious creatures called Mushi that exist in the natural world and influence the lives of humans in subtle, often inexplicable ways. Through a series of episodic tales, Ginko encounters various individuals affected by these ethereal beings, offering his wisdom and assistance to help them understand and cope with the strange phenomena. The narrative explores themes of coexistence between humans and nature, emphasizing the delicate balance and interconnectedness of all living things.