Kodama

Kodama (コダマ) was the apprentice of Mujika, a Mushishi who had become the guardian of a mountain.

Background
Kodama had been left on the mountain by his parents, who could not afford to take care of him. He was found by Mujika, and became his apprentice. However, his siblings died and his parents took him back. When Ginko went onto the mountain to find Mujika, he found Kodama first. Later, both Kodama and Ginko hear the sound of the Kuchinawa, and are the only ones to remember Mujika's existence after he is devoured.