The old Shugenja is a character from the Kishin Douji Zenki series. He is a distant descendant of Goki and thus also distant relative to Akira. While we get to know about their relationship, the old man's actual name is never mentioned in the series, where Akira just calls him "gramps".
The old Shugenja is a sturdy elderly man with a grey ponytail and a fluffy beard. He often wears a rather torn up and withered version of the traditional Shugendou garb worn by the Shugenja/Yamabushi. (a kind of Mountain Priest / Mountain Samurai)
The old man lives on Mount Oomine, the place where the Shugenja lived and practiced their aesthetics. At first he first appears to guarding Goki's grave, but we soon learn, that he was actually waiting for the azure Demon God Goki himself to return and arrive in the world of the living to continue fulfilling his role of the leader of the Shugenja.
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Manga
The old Shugenja doesn't appear in the manga, but he bears a resemblance to Shinsenbou, seemingly representing another aspect of him, while Shinsenbou himself is generally replaced by Miss Kazue, who is exclusive to the anime as well.
The old Shugenja serves as a connection to the past, allowing Akira to make contact with his roots as a Shugenja and his ancestors, which are otherwise not only completely missing from the anime, but also Akira didn't even know he was related to them till he met the old man.
Anime
Episode 29
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Ingame
The old Shugenja doesn't appear in any of the Kishin Douji Zenki games.
Gallery (Anime)
Episode 29
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