Gemini Kanon, the younger twin brother of Gold Saint Gemini Saga, emerged first as an antagonist. He embraced ambition, viewing their powers as divine gifts to exploit, and urged Saga to assassinate both Pope and infant Athena for control of Sanctuary. When Saga refused, he confined Kanon at Cape Sounion. There, Kanon uncovered Poseidon’s trident, shattered Athena’s seal, and triggered the sea god’s resurrection. Assuming the identity of Sea Dragon Marina General, he manipulated Poseidon’s forces, intending to overthrow both Athena and Poseidon for dominion over Earth. To maintain control, he suppressed Poseidon’s full awakening within Julian Solo. During the underwater war, he fought Phoenix Ikki, who exposed his deceit to fellow Mariners. After Poseidon’s defeat, Kanon sought redemption. During Hades’ invasion, he returned to Sanctuary and begged Athena’s forgiveness. She granted clemency, but Scorpio Milo demanded proof of loyalty. Kanon endured Milo’s Scarlet Needles without resistance, accepting the ordeal until Milo halted the final needle, convinced of his sincerity. Athena tasked him with defending the Gemini Temple. Wielding the Gemini Cloth and illusions like the Labyrinth of Twins, he stalled resurrected Gold Saints—including Saga—to buy time for Athena’s army. He confronted Saga, offering the dagger from their past assassination plot to reject their shared darkness. When Saga’s spirit departed, Kanon formally became Gemini Gold Saint. As Gold Saint, he joined the Underworld invasion. He mentally dominated Specter Balrog Lune to locate Judge Wyvern Rhadamanthys, then guided Bronze Saints Shiryu and Hyoga, shielding them while eliminating minor Specters. His clash with Rhadamanthys drew Judges Garuda Aiacos and Griffon Minos. After Ikki defeated Aiacos and Minos retreated, Kanon persisted against Rhadamanthys. When Gold Cloths resonated to aid Athena, he shed his Gemini Cloth and dispatched it. To destroy the Judge, he triggered a cosmic explosion, sacrificing himself alongside Rhadamanthys. His techniques included Galaxian Explosion, a slightly weaker echo of Saga’s attack. He wielded illusions like Genrou Ken and Genrou Maou Ken to ensnare foes. As Sea Dragon, he banished enemies to another dimension via Golden Triangle. He mastered astral projection to remotely command the Gemini Cloth and crafted complex illusions, such as the Gemini Temple’s Labyrinth of Twins. In the spin-off "Saint Seiya Episode G: Assassin," Kanon serves as Pope, assisting besieged allies and deploying the Gemini Cloth to support Saga.