Kanon de Gêmeos is the younger twin brother of the Gold Saint Saga de Gêmeos. Recognized as potential Gemini Saints upon arriving at the Sanctuary as infants, Kanon displayed a malicious personality early on, contrasting Saga's initial nobility. He urged Saga to assassinate Grand Pope Shion and the infant Athena to seize control. When Saga refused, he imprisoned Kanon in the inescapable Cape Sunion prison due to Kanon's dangerous ambitions. During imprisonment, Kanon encountered the goddess Ker, who revealed the malevolent entity Lemur had possessed Saga instead, explaining Saga's descent into darkness. Sustained by hatred and occasional intervention by Athena's cosmos, Kanon discovered and freed the Trident of Poseidon. It transported him to the Sunken Temple, where he broke Athena's seal on Poseidon's soul, presenting himself as the Sea Dragon General. He manipulated Poseidon's forces, intending for Athena's Saints and Poseidon's Mariners to destroy each other so he could rule both sea and land. After Poseidon's defeat, Kanon resurfaced during the Hades conflict seeking redemption. Athena forgave him, and he abandoned his Marine scales to become the legitimate Gemini Gold Saint, succeeding his deceased brother. To prove loyalty, he endured Scorpio Milo's Scarlet Needles without retaliation. Milo spared him by using a non-lethal pressure point, acknowledging Kanon's sincerity. Later, Kanon guarded the Gemini Temple against the specter-possessed Saga, Shura, and Camus. He created illusions to trap them, but Saga, knowing the temple's secrets, shattered the illusion and incapacitated Kanon. Saga internally approved of Kanon's redemption upon seeing the Gemini Cloth accept his brother. In the Underworld during the Hades - Inferno chapter, Kanon fought alongside the Bronze Saints. He defeated specters including Balrog Lune, Lycaon Phlegyas, and Deadly Beetle Stand. He then clashed with Wyvern Rhadamanthys, one of Hades' Three Judges, initially overpowering him. The intervention of Griffon Minos and Garuda Aiacos turned the tide against him. After Phoenix Ikki distracted the Judges, Kanon resumed his duel with Rhadamanthys. When the Gemini Gold Cloth was summoned by the other Gold Saints to help destroy the Wailing Wall, Kanon removed his armor and sent it away. He sacrificed himself using a suicidal technique, immobilizing Rhadamanthys and detonating his cosmos to kill both himself and the Judge. This act was his final penance. His soul later appeared briefly alongside Saga's during the Gold Saints' collective sacrifice to destroy the Wailing Wall. Kanon's techniques included the Galaxian Explosion, similar to Saga's though slightly less powerful, and the Genrou Ken (Illusion Fist), which manipulated opponents through illusions without requiring them to kill, differing from Saga's Genrou Maou Ken. As the Sea Dragon, he used the Golden Triangle to banish foes to another dimension. His personality evolved from treacherous and power-hungry to resolute and honorable after redemption, though he retained a ruthless pragmatism in battle, admonishing hesitation in allies. He ultimately sought atonement through self-sacrifice.