Gemini Kanon is the younger twin brother of Gold Saint Gemini Saga, sharing the same constellation and comparable cosmic power. Initially ambitious and manipulative, Kanon viewed their power as a divine gift to exploit for dominance. He urged Saga to assassinate the Grand Pope and infant Athena to seize Sanctuary. Upon Saga's refusal, Kanon was imprisoned at Cape Sounion. There, he discovered Poseidon's trident and orchestrated the sea god's premature resurrection. Impersonating the Sea Dragon General, one of Poseidon's seven Mariners, he manipulated the god's army to further his own goal of overthrowing both Athena and Poseidon, directly contributing to the conflict in Sanctuary and Poseidon's return. After the Bronze Saints thwarted Poseidon, Kanon survived and sought redemption. He approached Athena to request forgiveness and pledge loyalty. To test his sincerity, Gold Saint Scorpio Milo subjected him to the Scarlet Needle attack. Kanon endured the punishment without retaliation, convincing Milo to spare his life with the final needle. Athena then formally recognized him as the new Gemini Gold Saint, granting him Saga's former cloth and position. During the Hades conflict, as the Gemini Saint guarding the Gemini Temple, Kanon used the Labyrinth of Twins illusion to impede the resurrected Gold Saints Shura, Camus, and his brother Saga, who served Hades. He later presented Saga with the golden dagger from the failed Athena assassination. Kanon joined the invasion of the Underworld, displaying formidable prowess. He mentally controlled and eliminated Specters like Balrog Lune, overpowered Wyvern Rhadamanthys multiple times, and assisted Shiryu and Hyoga by defeating Specters such as Lycaon Phlegyas. His final act occurred confronting Rhadamanthys, aided by fellow Judges Minos and Aiacos. After Phoenix Ikki defeated Aiacos, Kanon re-engaged Rhadamanthys. Sensing the other Gold Cloths calling for the Gemini Cloth to breach the Wailing Wall, Kanon removed his cloth and sent it away. He sacrificed himself by unleashing a final Galaxian Explosion while physically restraining Rhadamanthys, resulting in their mutual annihilation, cementing his redemption and honored status. Kanon's techniques include the Galaxian Explosion, a devastating cosmic energy attack inherited from Saga though considered slightly less potent; the Genrou Maou Ken (Devil Emperor Illusion Fist), capable of manipulating opponents through powerful illusions without requiring them to kill; the Golden Triangle technique used as Sea Dragon to banish foes like Phoenix Ikki to the Bermuda Triangle dimension; Astral Projection to remotely control his Cloth; and the Labyrinth of Twins illusion within his temple.