[1] The OVA series was directed by Masahiko Murata (Jinki: Extend, Corpse Princess) and written by Satoru Nishizono and Shinzo Fujita.

Mazinkaiser emulates Go Nagai's character designs, and its operatic plot is supported by a "tongue-in-cheek" cynicism in regard to the gratuitous sex and violence.

It is explained that the Great Mazinger made by Doctor Kenzo Kabuto (Kouji's father) is the prototype version seen in the early episodes, whereas Doctor Juzo Kabuto (Kouji's grandfather), who secretly works in an underground laboratory, managed to finish the final version of Great Mazinger.

With a tremendous power compared to the prototype version, Tetsuya asked Kouji to confront Dr. Hell in Bardos Island.

Kouji, without knowing the true Shin Great Mazinger, was worried and asked Tetsuya if he can handle an entire army of super robots.

Consequently, Shin Great Mazinger defeated the entire army of Doctor Hell including the possessed Venus Ace (although most of the battle was not shown).

Before he can be killed by a gloating Ashura, a mystery robot wipes out the entire attacking Mechanical Beast army with one shot.

Episode 2: A Descending, Malevolent Deity: Great Mazinger attempts to battle the mystery robot, but is easily swept aside.

Because of this, when Ashura uses the aerial fortress Gool and to attack a nearby city Great Mazinger, Aphrodite A and Boss Borot are dispatched while Kouji helplessly fumes back in the lab.

Tetsuya decides to leave with Jun to give his wounds time to heal and entrust the safety of Japan to Kouji.

Ashura's daughters attack Boss by mistake, prompting Dr. Yumi and Sayaka to forbid Kouji from leaving the Lab until the situation changes.

The Photon Power Lab: Dr. Hell is fast losing patience with Ashura's failures, prompting the half-male, half-female villain to carry out a desperate plot.

In the course of the episode Dr. Hell chances upon a group of more powerful, partly organic giants (Mykene Warrior Beasts) which he utilizes in place of the previous mechanical monsters.

: Dr. Hell launches a full-scale assault on the Photon Power Lab, using the Ghost Mechanical Beast Drago Omega 1 to infect Venus A and turn it against them.

: After Mazinkaiser is dumped into Mount Fuji by the Combined Mechanical Beast, it pursues Boss, Sayaka and the other members of the Photon Power Lab.

While Great battles the Mechanical Beasts, Jun arrives and takes the group to the hidden fortress where Kouji discovered Mazinkaiser.

At that time, Dr. Juzo Kabuto, thought to be dead, was secretly making the final version of Great Mazinger in his underground laboratory.

After briefly assisting Great, Kouji decides to attack Dr. Hell's base, which was uncovered when he launched his entire Mechanical Beast army.

After a long and difficult battle, Kouji emerges triumphant thanks to Mazinkaiser's Final Blade and thoughts of his friends and family.