In the Andromeda galaxy there's a planet of a highly developed human civilisation. The gentle Prince Itaka and another kingdom's beautiful Princess Lilia are about to enter a love-marriage and take over the throne, when they discover a strange object on the nightsky. Later it lands on the planet, and an alien, mechanic civilization invades King Itaka's peaceful country making nearly everybody their slave. On a fateful night Queen Lilia gives birth to twins, and to avoid misfortune, the nanny Tarama takes one of the babies away, and entrusts it to the gladiator Balga. They still don't know, that the children were born with strong powers, and hold the key to the fight against the enemy that's searching to destroy every human civilisation on the planet...

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.

Luo Zheng, who is now a menial slave, used to be a young master of a big family. Owing to the decline of his family, his sister is imprisoned by a strong force, and he has no choice but to be at others' service. However, every cloud has a silver lining. The ancient book left by his father actually conceals a magical spell that can change a human into an instrument! What is the mysterious power behind this? This is contest with fate.

The main protagonist Sendou Aichi, is a timid and mundane third-year middle school boy. The thing that supported Aichi's heart, was the "Blaster Blade" card that he received as a child. It's an important rare card from "Vanguard", a card game with the imaginary world of "Planet Cray" as its stage. From the day he reunited with the person who gave him that card "Toshiki Kai", Aichi's everyday life began to change.