Three Kingdoms counterpart: Zuo Ci
Birthday: January 17
Horoscope: Capricorn
Age: 19
Height: 177 cm
Blood Type: O
School: Nanyou's Institute, 3rd Year
Toushi Rank: A-Rank

Manga
A third-year student at Nanyo Academy with blond hair and a light tan, and one of Nanyo's Big Four. He is one of Ryomou's oldest friends (whom he refers to as "Mou-chan"), and has feelings for both her and Housen Ryofu; even so, he is also a complete womanizer. His actual ranking as a fighter is unknown, as he never actually wears his magatama in public, but in fights he has shown himself to be an A-rank easily. One of his primary goals as Ouin was to remove Totaku from power, which, like his historical namesake, he accomplishes by convincing Ryofu to assassinate him.

In order to further Hakufu's mastery of the Water Dragon Fist, Saji fully donned the magatama and identity of Ouin, granting him great power and also slightly altering his appearance. Engaging Hakufu in deadly combat, he intentionally awakens her dragon, then, using his experience with Ryubi's dragon three years ago, absorbs the dragon's negative energy into himself, snapping Hakufu back to normal and placing the dragon's power completely under her control, though at the cost of losing one of his arms in the process. Infected with the dragon's evil and knowing he doesn't have much time left, he declares that he is no longer Saji but Ouin, and that he has already lived longer than he should have. Telling Hakufu not to cry for someone like him, he commits suicide by jumping off a nearby cliff in a manner eerily similar to Totaku's death, his last thoughts of Ryofu. At the same time, even though she was far away, Ryomou is suddenly struck with the knowledge that Saji would not be coming back.

Anime
In the anime adaptation, he is more sinister, even going so far as to have Kannei murder Enjutsu in order to take control of Nanyo for himself, the act of which driving Kannei insane. He has the power to hypnotize and control the minds of humans, treating them more like pawns than friends. He is more obsessed with Totaku's demise, and tried to take control of Hakufu as well, but failed when Totaku tried to possess her and was eaten by her dragon. He resolves to atone afterwards, and has secluded himself in the mountains somewhere. He reappears in Dragon Destiny in order to stop Koukin from traveling to Kyosho to stop Hakufu from fighting Kanu. When he returns, he immediately goes back to his womanizing ways, flirting with Ryomou, Ryubi, Chouhi, and Bashoku at separate points in the anime. He and Ryomou defeat Myosai at the Battle of Red Cliffs, and returns to his womanising ways again at the end of the series.

It is revealed in Great Guardians that there really is another fighter who goes by the name of Genpou Saji, revealing that Saji's name was actually not an alias. The real Saji meets with him and in exchange for reviving Ryofu, wanted to obtain Ryomou's dragon by putting on a lover's "act" for Ryomou, in order to build up her jealous emotions so that her dragon would be released. Ouin, for the most part, went with the plan. However, it was to save not only Ryomou and Ryofu but Saji herself as well.