Gakusanjin

is a rock yōkai in the form of a mountain who owns the Fuyōheki, which conceals his energy and lets him sleep eternally. However, Naraku steals the Fuyōheki to conceal his heart. Gakusanjin 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 because they are not able to make a distinction between evil demons and innocuous demons.

The corpse of Gakusanjin is discovered by the group of Inuyasha. Afterwards it turns out that Goryōmaru deposited the Gakusanjin carcass in a cave to create a strong concentration of demonic aura.

Media appearances
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Manga

 * Chapter 335
 * Chapter 336
 * Chapter 346
 * Chapter 347
 * Chapter 348

Anime
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 * Episode 165
 * Episode 166

Gakusanjin Gakusanjin 岳山人