Tōkajin

was a "man" who lived atop a cliff in the Togenkyo region, where he watched over the Ninmenka (human-faced peach tree). He used the Ninmenka to try and achieve immortality through the Fruit of Longevity.

Tōkajin would "save" defeated or defected soldiers who were lost and hungry from war, shrink them down to size and make them train to become sages in his miniature village. When one of his apprentices would gain even minor spiritual stature, they would be put in Tōkajin's gourd, dissolved inside it, and thereafter become nourishment for Ninmenka. In the manga, he uses a staff to shrink Inuyasha, instead of a gourd. As flowers spew from the staff, he told Inuyasha to "look closely", as they become bigger and as Inuyasha shrinks.

Manga vs. Anime
In the manga, the tree Ninmenka did not have the ability to speak, and Tōkajin stated that he learned all of his spells by reading forbidden scrolls, because even after a few years of training his hermit-master would not teach him anything more than minor sorcery. In the anime, however, there was a discussion of how the tree Ninmenka gained the ability to speak after receiving a sacred jewel shard, and that it was the demon tree who told Tōkajin about the fruit of longevity and taught him spells. Though in both adaptations, Tōkajin stated that the reason he kept his master alive was because the hermit-master was the only person who knew the only true method to reach longevity, but would not divulge the information, saying Ninmenka's method was far inferior.

In the anime, Tōkajin met his end as he was falling to his death during his battle with Inuyasha, and Ninmenka saved him, only to devour the "Sage" in order to gain precious nourishment and "the freedom of movement". In the manga, he simply fell to his death.

In the manga, this part of the story happened before Sango is introduced. In the Anime, it happened much later, after Sango's weapon was damaged and she left the group to go to her village to repair it.