Nui

Nui was a Mushishi and is the narrator of many episodes in the anime series. Nui makes her only in-person appearance in episode 12. She studied two Mushi : the Tokoyami and the Ginko that lived within it. Her prolonged exposure to the Ginko's light turned her hair to white and her left eye to green. It also made her lose her right eye. She found out that eventually all the creatures exposed to the Ginko's light turn into Tokoyami. One day, she found an injured boy named Yoki in the woods who had lost his mother in a landslide. She tended to his wounds and explained to him the nature of the Tokoyami. She then willingly exposed herself to the light of the Ginko and turned into a Tokoyami.