O-Balon the Sea Dragon (海竜 « オ=ベイロン »), also known as the Dragon of Prosperity, is one of the Five Dragons of Altago. He was revered by the people of Edonas, one of the Five Tribes of Altago. This custom has long been abandoned after the Edonians began worshipping the foreign deity Grattheos. This eventually saw the disappearance of the Edonas Tribe with the rise of the Kingdom of Altago, with their identity supplanted in being just Altaginians.

O-Balon is located in the Sea Sanctum which can be reached behind the Sea Altar on the Ruins Island. Adol first spoke to O-Balon on the former's first visit to the Sea Altar. On a second visit to the inner sanctum, O-Balon had to test Adol to see if he was worthy before granting him the Dragon's power. After being defeated, the dragon would condense himself into the Sea Dragon Stone and grant Aisha her Extra Skill.

After the defeat of the Root of All Existence, O-Balon departed from Altago along with the other dragons.

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