"Mushi": the world's most primitive forms of life. They exist without any aims or intentions other than simply "being," and they are free of the constraints of the labels "good" and "evil." Mushi may exist in various forms and are capable of replicating natural events such as plants, illnesses, and even rainbows. This is only a hazy characterization of the things that inhabit Mushishi's colourful universe; to term them a type of life would be an oversimplification. Because the majority of people are ignorant of Mushi's existence, detailed information about them is sparse. What exactly are Mushi, and why do they exist? This is the question that a "Mushishi," or Ginko, is continuously pondering. Mushishi are those people.