Mu shi shi.

They live on the shadowy border between the possible and the impossible--ancient life-forms known as mushi. Rare is the individual who can see them, but those with that special ability, the mushishi, can counter the creatures' deadly effects on humans. After a young boy is orphaned in the forest, he is saved by a reclusive female mushishi. But the lake near the mushishi's home holds a deadly secret, and the boy must find out what it is before his only friend is lost forever.