OVA
Description
Kanon di Gemini is the younger twin brother of Saga, the original Gemini Gold Saint. For much of his early life, his existence was kept a secret from the rest of the Sanctuary, where he was intended to serve as a hidden replacement for Saga should the need ever arise. Unlike his brother, who was known for his integrity and loyalty to Athena, Kanon was deeply ambitious and arrogant, believing that the immense power he possessed was a gift from the gods to be used for his own benefit. This fundamental difference in character led him to devise a conspiracy: he attempted to persuade Saga to assassinate the newborn Athena and the Pope to seize control of the Sanctuary. Horrified by his brother's blasphemy, Saga imprisoned Kanon in the stone prison at Cape Sounion.

During his imprisonment, Kanon was repeatedly saved from drowning by the divine cosmos of the infant Athena, a fact he did not realize at the time. He eventually discovered a hidden passage that led him to Poseidon's Trident and the undersea Sanctuary. Seizing the opportunity, he awakened the slumbering god Poseidon and, assuming the identity of the Sea Dragon, one of the seven Marine Generals, he manipulated the god and his army to wage war against Athena. His ultimate goal was to use Poseidon's power to destroy Athena, after which he planned to overthrow the sea god and rule the world himself.

After Poseidon's defeat, Kanon survived and sought to redeem himself for his past sins. He pledged his loyalty to Athena, but his change of heart was met with deep distrust from the other Gold Saints due to his treacherous history. In the Hades Chapter Sanctuary, Kanon takes on the role of the Gemini Gold Saint, guarding the Temple of the Twins in his deceased brother's place. When the resurrected Saga, along with other former Gold Saints turned Specters, attacked the Sanctuary, Kanon used his mastery of illusions, particularly a technique called the Labyrinth of Twins, to delay their advance.

His most significant act of redemption occurs when he is confronted by Scorpio Milo. To prove his unwavering loyalty to Athena, Kanon willingly endures Milo's Scarlet Needle attacks without offering any resistance. As he is pierced by the final, potentially fatal needle, Milo, having witnessed Kanon's genuine remorse, instead uses the technique to stop Kanon's bleeding, thereby accepting him as a true comrade. Subsequently, Athena entrusts Kanon with the golden dagger that Saga had once used in his attempt to kill her, tasking Kanon with delivering it to his brother, a symbolic act signifying both trust and closure.

Following the events in the Sanctuary, Kanon journeys to the Underworld to fight against Hades's army of 108 Specters. He proves to be a formidable force, using his cunning and power to dispatch numerous enemies, including controlling the Specter Balrog Lune to locate the Wyvern judge, Rhadamanthys. In his final battle, he confronts Rhadamanthys once more. As the twelve Gold Cloths resonate their power to destroy the Wailing Wall, a barrier that blocks the path to Elysium, Kanon removes his own Gemini Cloth and sends it to aid in the effort. He then sacrifices his own life by unleashing his ultimate technique, the Galaxian Explosion, while trapped with Rhadamanthys, destroying them both and allowing the other Saints to advance.

Physically, Kanon is nearly identical to his twin brother, being a tall and muscular man. He is typically distinguished by his slightly shorter hair and its deep navy blue color, which contrasts with Saga's cerulean blue. His personality is complex, initially defined by ruthless ambition and a belief that power is a tool for personal aggrandizement. He is a cunning and intelligent conspirator, capable of patiently orchestrating long-term plans to manipulate gods and armies alike. Even after his redemption, he retains a harsh and practical demeanor, chiding younger Saints for hesitation in battle and asserting that doubt is a weakness. This cruelty, however, is refocused into a fierce and unwavering dedication to Athena's cause, ultimately leading him to a path of selfless sacrifice that completes his atonement.

As a Gold Saint, Kanon possesses immense cosmic power and commands several devastating techniques. He can use Another Dimension to create spatial warps, banishing opponents to another dimension. He is also a master of illusions, capable of confusing his enemies within a labyrinth of his own making. His primary offensive techniques include the Genro Mao Ken, or Illusion Fist, which controls an opponent's mind by trapping them in a cycle of illusions, and his ultimate attack, the Galaxian Explosion, an incredibly powerful blast with the force to destroy stars. During his time as the Sea Dragon, he could also use a related technique known as the Golden Triangle, which sent foes to the mythical Bermuda Triangle.