Gakusanjin

is a rock demon whose form is of a mountain and owns the Fuyōheki, that conceals his energy and lets him sleep eternally. However, Naraku steals the Fuyōheki, using Parasite Chrysalis, to conceal his heart. He then helps Inuyasha and his gang to find Naraku, giving them a demonic aura crystal: if the aura disappears, the Fuyōheki will be near (The gang promises to return the Fuyōheki in return).

He is later killed by the Gyōja casually, because them are not able to make a distinction between evil demons and demons innocuous. The corpse of Gakusanjin is discovered by the group of Inuyasha. Afterwards it turns out that Goryomaru he deposited the Gakusanjin carcass in a cave to create a strong concentration of demonic aura.

岳山人 Gakusanjin