Zau Zau was the Monster of the week on Ep. 32 of the Grendizer Anime, and was piloted by the Ep. Main antagonist, Commander Marianne. It's vehicle form was a bit more rounded than the general flat disk, color Pink on top with Green at the bottom, with a black and Green mint mid section with a row of portholes all around, and two missile shafts. The Beast form comprise of the Red Dragon's head with white horns and spikes, orange eyes and a long purple neck, dark color boosters for legs and a purple tail. Zau could generate holograms from the main spike and fire a energy beam from the smaller ones; breath red color Proton Fire; fire energy projectiles from its portholes and rockets from the missile shafts on the sides and use its legs as projectiles in case been severed. If the body is destroy, the head can separate and continue on fighting.

Zurin gives a demonstration to Gandal of the Mirage Generator on a Earthling Jetliner (creating floating islands and flying fish) confusing the occupants, the new weapon been installed on the new Beast (Zau); he then introduces the agent for the mission task to kill Duke, Commander Marianne, who has a resemblance to the late Queen of Planet Fleed (Duke's mother). Interested in seeing her skill, Gandal orders a Soldier to attack her, only to stop and burn down to ash; Zurin reveals Marianne holds a ring made of pure Protons, burning anyone and anything she touches. Please with her performance, Marianne is dispatch to Earth on Zau Zau to proceed with her mission.

On the Makiba farm, Daisuke arrives to find a fight between Goro and his father Dambei, for a picture he drew of his late mother. After talking with Goro, Daisuke is reminded about his when the Observatory calls him about the incoming UFO and leaves to deploy Grendizer; while in the lab, Koji an the Staff installed onto the the Jeep a new weapon of his design, the Cyclone Beam (which is powered by nuclear generator), when the alarm is sounded off. Duke deploys Grendizer to confront the Invader.

Zurin warns Marianne and deploys the Mirage Generator, creating copies of Zau Zau which Grendizer, of course, attacks with little success, when the real beast attacks with is energy projectiles and rockets. Grendizer misses the attacker into a cloud cover only to find his old Home city from Planet Fleed on Earth (obviously, created by the Mirage Generator) and lands to investigate, the lab unable to contact Duke due to Signal Jamming and Koji leaves to help Duke with the new Weapon. Exploring the place his stumbles upon his mother (the Commander in disguise), and a baffled Duke demands answers, with her replying been revived by Vega Science and attempts to ask for a hug.

As she attempts to approach, however, Duke's Radiation wound from the Proton Bombs begins to hurt him, indicating the presence of a Proton Source (the ring) and Duke sees through the charade, telling her the truth about his wound; with her cover blown, Marianne lunges onto him and Duke jumps out of her way to see her burn one of the buildings into ash with her ring. Duke then looks around and sees a building with a strange glow and fires at it, destroying the Mirage Generator and lifting the illusion over the area and on Marianne; the Commander then throws a Proton Grenade and uses it to escape, reporting the situation to her superiors and vows to give her life by destroying Duke with the Proton Bomb Flame.

Duke board Grendizer when Marianne (on the Zau) appears and the Mecha's fight, where Marianne uses the Proton Fire, though avoids it, the close proximity continues to hurt his wound. Umon recommends to attack her from both ends and Duke ejects Grendizer, calling the attention to himself; He rapidly uses Spin saucer, cutting the forward legs, though these try to attack Grendizer, been block by Double Harken. Duke then unleashes Anti-Gravity Storm on Zau, causing it to crash, then fires Screw Crusher Punch, destroying the body but Marianne detaches the Head Cockpit to continue the fight. Grendizer connects with the Spazer, but Marianne continues to use the Proton fire, blocking the Melt Shower attack.

She then covers Grendizer with Proton Fire, making great pain to Duke, causing to fall unconscious. Koji arrives as Marianne kamikazes towards Grendizer. Koji deploys the Cyclone Beam Gun shutting the craft down and killing Marianne. Duke thanks Koji and returns back to the lab to be treated. Afterwards, Goro shows him a better picture of his mother, pleasing Daisuke, who looks to the sky, reminded of his mother one more time.