Within mangaka Eiichiro Oda’s original One Piece story, one of the most mysterious groups of characters is known as the Gorosei. Despite first appearing in chapter 233 of the manga, fans wouldn’t learn anything significant about them for nearly 21 years and over 800 chapters afterward. More specifically, fans first learned their names and official titles in the Egghead Arc.
One of the most significant members of the Gorosei is none other than Saint Jaygarcia Saturn, Warrior God of Science and Defense. Saturn serves as the primary antagonist of the Egghead Arc, which is also where he is individually named for the first time. The arc later introduces the other Gorosei members during a flashback sequence to the Reverie Arc’s events.
As a member of the Gorosei, Saturn’s primary role in the series is running the World Government in accordance with Imu’s will. He also holds a great deal of power himself, being able to directly command virtually any of the World Government’s forces. Likewise, his role in the Egghead Arc is overseeing the Buster Call assault on the Straw Hats and Dr. Vegapunk.

However, he eventually gets involved in the fighting himself, marking the first time in all of One Piece where one of the Gorosei is seen fighting. While there isn’t much known about Saturn’s history, it is confirmed that he was alive 200 years prior to the current story events. This essentially confirms that Saturn has some kind of immortality, likely granted through Imu.
Beyond this, Saturn is known to be a genius scientist himself, proclaiming as much when speaking with Dr. Vegapunk. He has also performed experiments involving Devil Fruits and the Sapphire Scales disease. His eavesdropping on Dr. Vegapunk’s conversations, as seen in flashbacks, and his general understanding of World Government tech further show his genius.
Saturn’s powers and abilities in One Piece
As mentioned above, Saturn is confirmed to be immortal in One Piece, although exactly how he attained this immortality has yet to be officially confirmed. However, it’s heavily implied that this power is achieved through his loyalty to Imu. Saturn is also confirmed to be able to use Observation and Conqueror’s Haki, though he hasn’t been seen using Armament Haki yet.
Saturn also possesses incredibly unique powers, such as regeneration, which is presumably intertwined with his immortality. He’s also capable of using telepathy to communicate with both the other Gorosei members and Imu themselves. Saturn can also use the Abyss teleportation technique, which involves emerging from pentagram-like magic circles.
While Saturn does appear to have Devil Fruit powers in One Piece, they have yet to be explicitly confirmed as such. His ability is first named in chapter 1110, and is simply identified as “Gyuki,” a reference to the yokai from Japanese folklore of the same name. The yokai is also known as an “ushi-oni,” typically depicted as a monster with a bovine head and spider-like body.

Should Saturn’s powers be confirmed as originating from a Devil Fruit, it’s all but guaranteed to be a Mythical Zoan-type. Saturn’s powers are also heavily implied to be Awakened, or rather the equivalent of an Awakened Devil Fruit, by the nature of the black cloud scarf he’s seen with. Saturn’s Hybrid and full Beast Forms were seen during the Egghead Arc’s battles.
Saturn’s powers in One Piece have been shown to give him sharp claws at the end of his spider-like legs. These claws are also poisonous, and he can even spit venom, which can cause explosions upon impact. Saturn’s legs can also move freely as if they were tentacles, and he also has an unnamed invisible “force” which can be used to restrain or attack enemies.
In summation
Saint Jaygarcia Saturn is a Gorosei member who serves as the primary antagonist of the Egghead Arc. He is confirmed to wield both Observation and Conqueror’s Haki but has yet to use Armament Haki. He’s also heavily implied to have a Mythical Zoan-type Devil Fruit. Saturn is also a genius scientist and is essentially one of the World Government’s public ruling faces.