Mujika was a mushi-shi from the Mushishi anime and manga. He debuted in the episode The Sleeping Mountain. He was notable for acting as a messenger for the Master of the Mountain, when he secretly acted as that creature thanks to his connection with the creature.
Before becoming a mountain being, Mujika was a wandering mushishi who was good friends with a woman named Saku. He was asked to stay, and although he wanted to, he couldn't. He claimed the only way to stay was if the mountain master were killed and he ate the flesh so that he would gain powers over the mountain. Saku heard this statement, and the next morning she took Mujika's poison and map of the mountain. She killed the master (which was in the form of a boar), and begged Mujika to eat the meat and stay. He later married her and the two lived on the mountain. However, she died because she could not handle the mountain's energies.
Since his turning into the mountain master, strange occurrences happened in the mountain, such as finding foxes with ape faces and seeing a perfect circle cut in a mountain. Mujika found a boy who was abandoned in the village (due to overpopulation), and trained the boy to be a mushishi. The boy was then retaken by his parents, but he remained Mujika's apprentice. After Ginko came, Mujika called a Kuchinawa that came to devour him and take its place as the mountain master, thus restoring the natural order of things. However, after he was consumed by the mushi, he was forgotten by all who were not upon the mountain at the time of his disappearance. Thus, Ginko and Kodama, the apprentice, were the only ones who remembered him because they were currently on the same mountain.