In Thrace, Arion is taken from his mother Demeter by the god Hades. In the Underworld, Arion is trained to be a warrior. His training is driven by revenge: Arion was told that his mother's blindness was caused by Zeus and Zeus' death will remove the curse. Finally, Arion and Geedo (a huge ape-like creature who had become Arion's friend and companion) left the Underworld to find Zeus. Seneca, a small thief, makes off with Arion's sword and this leads Arion to his first encounter with the forces of Zeus, commanded by his daughter Athena. Arion is captured but is later set free by Lesfeena, Athena's mute serving girl. As Arion rejoins Geedo and Seneca (and worries about Lesfeena), the forces of Zeus and Poseidon face each other in battle. In the background sits the scheming Hades, and the calm Apollon who seems to have plans of his own.

Five supernatural factions have been fighting against each other for who knows how many centuries, with the beginning of Aquarian Age always in mind. Kyouta, soon begins to see visions of mystical girls fighting, except they do exist. Soon he and his girlfriend Yoriko become involved and the battle for Earth and Aquarian Age lies in their hands.

Seventeen-year-old Marco Polo leaves his home in Venice on a trip to the little-known country of "Yuan", in the company of his father Nicolo and his uncle Matteo. Their mission is to deliver the sacred oil from the Tomb of Christ and a letter from the Pope to the Kublai.

A sequel to Aki-Sora under a new name.