There's a crisis in the Chinese Spirit World -- humans don't believe in gods anymore! A Door God, facing unemployment, ventures into the human world to prove his worth, leading to unexpected encounters and transformations for humans and spirits alike.

Alien invaders take over Great Mazinger who is at the entrance of a museum next to Mazinger Z as symbols of peace. Grendizer fights the evil invaders and Great Mazinger is recovered. 

When the Vegan empire dispatches a new general to oversee the takeover of Earth, he quickly manages to capture Koji Kabuto and, learning of Great Mazinger through interrogation, quickly commandeers it from a museum where it was kept as a symbol of peace. 

It is now up to Duke Fleed aboard Grendizer to stop humanity's former defender from becoming its destroyer.

(Source: ANN)

Mito isn't just another space pirate, she's a three foot tall childlike alien with enough guts to outshine a supernova. She's known as the galaxy's most dangerous pirate, a wanted criminal who destroys a dozen police space cruisers every day before breakfast. But all she really wants is to be called "Mom." (Source: ANN)

Time flies by; Hiroyuki and Akari are 12th-graders now. Both of them and their friends have grown up gradually in someway, physically or mentally, but one of their best friends is missing: the lifelike android Multi. To their surprise, Multi is brought to their campus again without notice, yet she is no longer the same Multi they have known.