Marigera was an Intelligence Army Warrior Beast and main Monster of the week on Ep.50 of the Great Mazinger Anime, and among a few to be female. She is unique among all the Beasts, as she was purely mechanical and operated by command, rather than the brain that controlled it, as it was with the other Warrior Beasts. She became the holder and prison of Yuko Moriyama, Shiro's School Teacher, and while she could communicate with everyone she contacted with, Moriyama could not control the Beast from Marquis Janus' commands, making for a dangerous hostage situation. Despite the teacher's brain been a key component, unlike other Warrior Beast, Moriyama was not infused into the body of the Monster (as seen in the creation of Jerunicas), Moriyama was in fact locked inside the monster in a capsule in semi unconscious state, been aware of her surroundings through the monster's true face.

Marigera had almost the same color scheme as the late Aphrodite A, Red with Yellow, though hue in tone with bright red in the front portions, and with a define face with a dark yellow forehead, with white breasts. She also had high heels in her shoes, pearl like jewelry in her writs and a black waist. Her arsenal includes Two Boomerang blades which hang from the side of her head, an energy beam, which is cause by her crossing her arms in an “X” shape pattern, Missiles (which come out from the knees), a tentacle which pops out from the top of her head and a fan, that came out from the real head, as well disperse a glue like substance from the breast (I'm no kidding), as well projectiles. Marigera's true face was located in the lower torso, and was light and dark blueish green in color, resembling Moriyama herself.

For sometime, Shiro has been coming home late, having befriended the newest teacher – a young woman by the name of Yuko Moriyama, who has something of a motherly persona towards her class, this trait of Moriyama been the reason why Shiro visits her, as it reminds him of been with his mother, something she can relate to, having lost her mother at a young age. Unfortunately for Moriyama, after Shiro left with Tetsuya, she receive the unwelcome visit of Marquis Janus in the middle of the night, she had kept tabs on the Young teacher for sometime – Janus knocks Moriyama out, storing a devious plan for her in the next scheme against Great Mazinger.

When Moriyama did not come to tent class the next day, Shiro went to her apartment building with Jun, but the building is torn apart by the awakening Warrior Beast Marigera. Janus appears making the reveal of the Beat's identity as Moriyama, and while Shiro tries to help her out, he is kicked by the beast, Moriyama having no control over it despite her brain been the key component. The Science fortress becomes alerted by the new Beast and Tetsuya goes takes off on the Great Mazinger. He proceeds to fight Marigera, but Shiro informs of the Beast's identity as his Teacher, Prof. Kabuto surmising that she was inside the beast itself and orders that X-Ray machine be installed onto the Queen Star.

Marigera pins Great down on many occasion, Tetsuya been unable to fight back do to the Hostage situation at hand, in the scuffle the Beast destroys Great's Typhoon Emitter and the arm off. Kabuto realizing the severity of the situation, orders Tetsuya to fight, much to Shiro's protest, saying “You wouldn't be so cold if you weren't a cyborg!”.

OUCH!.

Shiro then takes off on the Robot Jr, with Borot accompany him. Tetsuya finally takes the fight, and outmaneuvers Marigera, ripping the head off by pulling it with the tentacle, and attempts to use it as a flail, but Shiro tries to stop him, Borot sticks in between them, also trying to find a way to save Moriyama, but is shutdown by the beast. Tetsuya goes on the attack, Shiro tries to stop him only to be pushed away by Great, Shiro falling out of the cockpit in the impact, still Shiro cries to Tetsuya to not killed her. Seeing this, Great grabs hold onto Marigera, and Moriyama speaks to Shiro, unable to find where she was exactly inside, she decides to accept her own death if it meant stopping her from killing more people.

At that moment, Venus arrives and uses the X Ray, Tetsuya moves to cut Moriyama free with the sharp Blade of his wing, only to discovered she is trapped inside a capsule the moves in upward/downward pattern in a fixed track, Tetsuya avoid hitting her on time and pulls back, but this allows Marigera to continue her assault on the Mechas. Kabuto studies the rhythm and speed of movement and tells them to hold on to the beast for an assault with Great Booster. Venus grabs onto the Beast firing the X rays, while Great docks with Booster, for the fixed launch. Tetsuya studies the movement of the capsule, Venus jumps out of the way as he fires the Great Booster, cutting the Torso and avoiding Moriyama completely, freeing her and she falling off from the capsule, unconscious. Shiro runs to awake Moriyama. Great grabs the two just as the Beast's body explodes, saving their lives.

Later, after been treated from her wounds, Shiro walks with Moriyama, as the others are left thinking about the value of Human life, a thought more deeper for his father Kenso, do to his personal scars.