Jaki is a character from the anime adaptation of Knights of the Zodiac, known in the original Japanese as Saint Seiya. He appears as a formidable antagonist during the Sanctuary arc, specifically in the anime-only sequence as the Bronze Saints begin their assault on the Twelve Temples.

Jaki is a renegade warrior and a soldier of the Sanctuary who, despite possessing immense physical abilities, was never allowed to become a true Saint of Athena. The reason for this exclusion lies in his fundamentally cruel and violent nature. He is described as a giant of a man with an incredibly muscular build, dark skin, and messy blonde hair. His face is said to be deformed, giving him a beast-like appearance that matches his savage personality.

His character is defined by a profound and unrestrained sadism. Jaki is utterly merciless and takes great pleasure in inflicting suffering on others. He enjoys causing massacres purely for his own entertainment, a trait that the narrative emphasizes makes him the most cruel and violent man to have ever passed through the Sanctuary. This love for killing is so central to his being that he admits he accepted a mission from the Pope not for a reward, but simply for the opportunity to kill someone. He shows no pity for anyone, including women, as demonstrated in his brutal confrontation with Marin, the Silver Saint of Aquila.

In terms of his role in the story, Jaki appears as an obstacle for Marin. He intercepts her on the path to the Sanctuary while she is trying to rejoin the Bronze Saints. The Pope has promised to make him a Saint if he kills Marin before she can meet up with them, but Jaki reveals this is a lie; he only agreed to the task because it grants him a sanctioned excuse to murder. This fight serves to showcase his raw, brutish power against Marin's more refined technique.

Jaki's primary relationship is with Marin of Aquila. He is her direct antagonist, and he takes a sadistic interest in her because she is the teacher of Seiya of Pegasus. He taunts Marin with the information that Seiya is fighting for his life against Aiolia of Leo, seemingly to break her spirit before physically breaking her body. His cruel fixation extends to her Silver Saint mask, as he confesses he would love to see her face as he slowly crushes her to death.

The character does not undergo any development, as he appears in only a single episode as a minor antagonist. His story ends in his fight with Marin. After brutally beating her and trapping her in a powerful bear hug, he begins to squeeze the life out of her. However, Marin uses her agility to her advantage. By throwing her weight backward, she unbalances the giant, causing them both to plummet over a cliff. Jaki dies upon impact with the rocks below, while Marin survives.

Regarding his notable abilities, Jaki relies almost entirely on his overwhelming physical prowess. He possesses superhuman strength, which he demonstrates by throwing a massive boulder, hurling Marin against a stone wall with a single hand, and holding her in a grip from which a Silver Saint cannot break free. His physical power is explicitly stated to be comparable to that of a Silver Saint, making him by far the strongest of the common Sanctuary soldiers. While most warriors in the series manipulate their Cosmos, the inner energy of the universe, Jaki does not display any visual manifestation of this power. It is left ambiguous whether he uses Cosmos unconsciously or if his immense strength is purely a product of his giant physique, a rarity in a world where spiritual energy typically reigns supreme.