Yakurōdokusen

was a drunken sage who helped Sango repair her damaged Hiraikotsu. He dissolved Hiraikotsu into a jug and told Sango to go into a second jug and battle the demons inside, warning her that if she failed to defeat them then Hiraikotsu would be no more. Sango goes into the jug in order to battle the demons, who angrily demand to know why she sacrificed them; Sango quickly realizes that these demons are the same ones whose bones were used to create Hiraikotsu. After a short battle, the demons ultimately decide to rejoin Sango once again as Hiraikotsu; while having repaired Hiraikotsu, Yakurōdokusen's potions also made Hiraikotsu a much more powerful weapon, it now had the ability to absorb and disperse poison, making it a very formidable weapon.

Yakurōdokusen also gave Miroku an antidote that dulled the pain in his poisoned arm, meaning that he would no longer feel any pain whatsoever, although it did not completely heal him and the miasma was still spreading throughout his body.

Personality
He was a temperamental person as he would only assist people with whom he liked. He initially refused to restore Hiraikotsu because he thought it belonged to Inuyasha, and he hadn't taking a liking to him when they met. He was known to be very perverted, having a lecherous personality much like Miroku. This quality caused him to hit it off with the young monk, with Shippō commenting, "If by good man you mean pervert, then yes." He was a very heavy drinker that made it hard for him at times to focus.

Powers & Abilities

 * Potion Brewing: He is capable of brewing many remedies and poisons that has unique properties. All of his potions were interconnected with each other. When the poison that Miroku drank became a remedy, the poison that Hiraikotsu was brewing in became a remedy as well.
 * Limb Extension: He is able to stretch his arms to incredible lengths. He normally uses this ability to reach for objects that were further away.
 * Tongue Manipulation: He possesses a long retractable tongue which is able to detect poison that contaminates an object or a person.

Trivia

 * His seiyū, Minoru Inaba, also voiced a doctor in the short stories Middle-Aged Teen and One Hundred Years of Love as part of the Rumiko Takahashi Anthology, Sōkichi in Mermaid Saga and Kuroida in Rin-ne.
 * Since the Master of Potions also possesses a long retractable tongue which is able to detect poison that contaminates an object or a person, just like Tōtōsai, they may be the same species of Yōkai.

Media appearances
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Manga

 * Chapter 485
 * Chapter 486
 * Chapter 487
 * Chapter 488
 * Chapter 489
 * Chapter 498

Anime
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 * Episode 179
 * Episode 181

Yakurōdokusen Yakurodokusen 药老毒仙