Set in the early 24th century against the backdrop of the city of Neo Venezia on the planet Mars. No longer the barren red planet, Mars has been flooded, inhabited and is something of a tourist hub for those looking for rest, relaxation and a gondola ride – the primary mode of travel in Neo Venezia. The Undines are professional gondoliers, tour guides for the people passing through. Akari Mizunashi is an Undine in training and this is a piece of her story.

When Saki Morimi gets into trouble with the police while in Washington D.C., she is helped by a Japanese man who calls himself, Akira Takizawa. Akira has only two things, a gun and a cell phone loaded with 8.2 billion yen in digital money.

An art student named Jin Mikuriya carves a statue from the wood of the Kannagi tree only to have the statue come to life in the form of a goddess, who has now taken over the statue. He and "Nagi" work together to destroy the impurities that are gathering in the town.

Developed from Japanium ore is the super energy, Photon Power. Seeking this energy is Dr. Hell, a madman craving world domination who along with his subordinates Baron Ashura and Count Brocken, commands the Machine Beasts excavated from Bardos Island (believed to be Rhodes) to attack the Photon Power Lab and take it for himself. Meeting the attack head on is our hero, the hot-blooded teenager Kouji Kabuto who pilots the super robot Mazinger Z, constructed by his grandfather Juzo and made from the strongest metal Chogokin Z. But in this battle between Dr. Hell and the Kabuto family, many legends surrounding the Mycenaean Civilization and Bardos Island, as well as the secrets of Mazinger Z remain shrouded in mystery.