Saiga is a normal high school student with a gift in mathematics. His daily routine is disrupted when his family gets news that his Father's remains have been discovered—a noted archeologist and researcher who had gone missing while exploring a site many years before. Among his remains were notes and artifacts that needed to be identified by the family near a notable triangular mountain in Japan known as "Japan's pyramid", a place suspected by some to be man-made. A meteor containing a strange robotic lifeform falls from the sky and begins to cause destruction, putting Saiga in danger and causing a mysterious bracelet from his father's research to activate and merge him with an ancient robot burried within the pyramid—a robot the runes describe as Reideen. It is now up to Saiga and guardian Reideen to fight against this unknown alien threat from the sky. (Source: ANN)

Two advanced civilizations, the Paranoids (a race of alien humanoids) and the Solenoids (who are all women) are waging a war that has gone on for centuries. When the Solenoid fleet leaves a battle to defend an experimentally terraformed world from the Paranoids, one damaged Solenoid ship, the Star Leaf, is separated from the fleet. Only seven women remain alive on the ship: Eluza, the captain, Rabby, the solid more or less main character, Lufy, the brash pilot, Catty, the mysterious science officer, Pony, the pink-haired ditzy tech, Patty, a solid crew member, and Remy, the cute one. After narrowly escaping the battle, the crew of the Star Leaf decides to continue with their orders and rendezvous at planet Chaos to defend it. It turns out, however, that their ship is the subject of a Paranoid experiment. In the end, it is up to the remaining crew Star Leaf to defend the artificial paradise of Chaos from the Paranoid fleet and the plans of the Solenoid leaders.

Set a few months after the original series, Wataru is called into action once again!

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.