Basically every episode of Mushishi tells a self-contained story that involves, but is rarely about, a titular Mushi-shi called "Ginko" (this is not his name). Mushi, which means "insect" in Japanese, are mystical organisms that affect human health in various ways, but are really representations of various human behaviors in this show. Bigotry, drug addiction, love, loneliness, escapism... nearly every aspect of the human experience is explored through this framing device. "Ginko" travels around Japan, aiding people who have succumbed to these "mushi" to overcome their problems, all the while maintaining a fascination with mushi themselves and his fellow humans. There are even hints of romance here and there, but Ginko's nomadic lifestyle precludes close relationships.
Each episode is its own story, telling a tale of some problem, whether a mental health issue, a societal one, etc., through the lens of a Mushi infection or infestation, and Ginko shows up to help, or just as often, to simply observe. Through it all, a fairy-tale like mystery is exuded regarding the true nature of not only these "mushi", but the humans that they affect. If you enjoy philosophical works that have little interest in holding your hand, Mushi-shi is a series I'd highly recommend. But if you prefer something more concrete, more story driven, and less ambiguous in its themes, then I'd suggest you avoid it. It is a masterpiece, in my estimation, but it is certainly not for everyone.
