Poseidon

is the god of the oceans and one of Olympus. he is the first god to start a crusade against Athena, during the First Crusade, where he built the great walled city Atlantis in the Atlantic Ocean. Later, he claims sovereignty of Attica on Earth,

His seal on the Trigeminal Halberd was removed by Kanon while imprisoned in Cape Sounion 13 years prior to the events of the Marina Generals Arc. After waking imperfectly, he inhabited the body of Julian Solo when he was 3 years old. After 13 years since then, a crusade against Athena was carried forward as Poseidon flooded the world with torrential rains. During the final battle, Poseidon's might fully awakened, allowing him to easily dispose of the Saints. He confronts Athena after she was rescued by Seiya from the Main Breadwinner. In the final confrontation, Poseidon's soul was torn from Julian Solo's body and imprisoned in Athena's jar once again.

In The Hades Chapter and Soul of Gold he helped the Bronze Saints sending by sending Gold Cloths to Elysium after contacting the Gold Saints revived while in Asgard after the battle against Loki.

Kurumada said Hades and Poseidon joined together to battle against the Saints and Zeus.