Yōreitaisei

was a yōkai hermit who taught Inuyasha about absorption of Yōki and how to keep control over it.

History
Due to Tessaiga having reached its new form as the Dragon-Scaled Tessaiga, Tōtōsai sent Inuyasha to him in order to train so he could use it without it backfiring. Mō-Mō led Inuyasha and his friends to the village where the demon hermit resided. When Inuyasha reached said village, he underwent a tricky test with which Yōreitaisei was helping Inuyasha to discover the existence of whirlpools of demonic energy known as Yōki, that he could cut through with his Tessaiga now in order to quickly defeat his enemies.

Trivia

 * His seiyū, Ichirō Nagai, voiced several characters from Rumiko Takahashi's previous series. They include Cherry and Sakura's Mother from Urusei Yatsura, Happosai from Ranma ½, Coach Mukoda in the One-Pound Gospel OVA, and the narrator in the short story As Long As You Are Here as part of the Rumiko Takahashi Anthology series, Rumic Theater.

Media appearances
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Manga

 * Chapter 426
 * Chapter 427
 * Chapter 428
 * Chapter 429
 * Chapter 430
 * Chapter 431

Anime
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 * Episode 5 (FA)

Yōreitaisei Yoreitaisei 妖灵大圣