It isn't unusual for a person to feel that the world around them is strange and has unexpected secrets lying just beyond their sight. However, for most people this is just an occasional sensation that greets them upon awakening or chases them into sleep. For the mushi researcher Ginko, it isn't a feeling at all; it is a knowledge which guides his travels and motivates his life. Found in the cracks between what is conceivable and what is not, are the varied life forms collectively known as mushi. They surround us and affect us, but their intensely different nature makes them unrecognizable to most. Ginko brings these life forms into perspective for the lives of those most affected and most in need of an explanation.
I'd recommend Mushishi for fans of Moyashimon R who really enjoy the parts of the plot that involve seeing bacteria. Mushishi's main character sees mushi, otherworldy creatures, and both shows are fairly light.