To increase their power, Kenji Tsukigata and Rui Senda both have their bodies modified. Obsessed with beauty, Kenji becomes Dr. Kemp, who can turn into a Beauty Beast when battle demands it, while Rui installs weapons all over her body and becomes the half-machine Dr. Mazenda. Only Gou Omura seems to have undergone no modification at all.

In fact, Gou's plan is even more radical than theirs! Convinced that the strength of the human body is limited, he resolves to abandon his human body and become a complete beast. To carry out this plan, he creates the Virus Brain, which injects young people with an experimental drug. The plan is eventually uncovered by Liveman, who track down Gou's secret laboratory.

By then Gou has already injected himself and his body is starting to change. The transformation leaves him in agony, and Jou Ohara, unable to bear seeing his suffering, decides to save him. Back at Academia, Gou and Jou had been close friends; Gou had once jumped into the sea to save a puppy, completely forgetting that he could not swim. Jou cannot believe that someone once so kind could have become a demon.

Jou manages to take Gou away, but the transformation succeeds in the end, and the beast man with the strongest body and power, Dr. Obular, is born! Obular attacks Jou without mercy. Left with no other choice, a heartbroken Jou holds back his tears, transforms into Yellow Lion and fights his old friend to the death.

Volt sends out the Baboon Brain to wreak havoc and bite people, and anyone it bites turns into a vicious ape-man. Faced with ape-men who were once innocent people, Liveman is at a loss. Together with the Baboon Brain, the ape-men gradually gain the upper hand. Just then, a burly man rides a motorcycle straight into the Baboon Brain! His name is Arashi Busujima, leader of a violent gang, and he is furious that the Baboon Brain has wrecked his turf. Busujima shows no fear of the Brain Beast, and his relentless attacks end up taming it! With this powerful new henchman at his side, he even plans to use it to rob a bank.

The three Liveman members arrive and try to stop him, but Busujima, who has always hated clever people, will not listen. At that moment Gash, who always stands guard beside Great Professor Bias, appears, defeats Busujima and carries him off. The Baboon Brain is destroyed by Liveman.

Bias had taken a liking to Busujima's ferocious nature and decided to make him his fourth disciple. He personally gives Busujima a genius education, and in a short time this brainless but brutish gang leader becomes a true genius, with an intellect no less than that of Kemp, Mazenda or Obular! Busujima goes on to modify his own body and becomes Volt's new officer, "Dr. Ashura"!

After one failed operation after another, Bias begins to doubt his disciples' abilities, especially Obular's.

To win back Bias's trust, Obular racks his brains for a new plan to defeat Liveman and conquer the world. He extracts his own genes to create the Study Brain and pours all his power into it. Exploiting children's eagerness to study, the Study Brain hands out copies of the "Volt Bible". Anyone who reads it is brainwashed and swears loyalty to Volt.

Yusuke and the others discover the plot and move to stop it, but the Study Brain is so powerful that even Liveman is no match for it. Just as the three warriors are about to lose, the Study Brain suddenly stops attacking and starts to play. Yusuke and the others seize the chance and turn defeat into victory, leaving Obular furious. What is more, having used up all his power creating the Study Brain, Obular reverts to his original self, Gou Omura!

Unlike Kemp and the others, Gou was not a born genius; everything he had was earned through hard work. Raised by his mother alone under a very strict upbringing, he never dared to slacken, always working hard and sacrificing every childhood pleasure to gain his abilities. Deep in his heart, however, he never forgot how hard studying had been, nor the childhood longing to play that he had always suppressed. The Study Brain, created from Obular's genes, was influenced by this subconscious, and so Obular's entire plan collapsed.

Meanwhile, alien geniuses from outer space join Volt out of admiration for Bias: first "Guildos" from "Planet Guildo", then "Butchy" from "Planet Chibuchi". With Volt now full of talent, there seems to be no place left for Obular. Displeased by this latest failure, Bias decides to expel Obular from Volt!

Back to being an ordinary man, Gou does not give up. Returning home, he begins researching how to become Obular once more. Jou and the others try their best to stop him, but Gou ignores them. Finally, in front of his mother, Gou becomes Obular again! But just before his duel with the three Liveman warriors, Kemp, Mazenda and Ashura ambush him together and use an "Obular Brain", created from his extracted genes, to take the place of the real Obular! Unwilling to let the Obular Brain steal the glory of defeating Liveman, the real and fake Obulars fight each other. Gou's mother arrives and pleads with her son to give up the fight, and her words finally move him. Shielding his mother, Obular is badly wounded. Exhausted in body and mind, he turns back into Gou Omura, losing all his memories and showing no response to anything.

Yusuke and the others defeat the Obular Brain and are saddened by what has happened to Gou. Yet they take comfort that mother and son are reunited and can live a quiet life together, and they believe that one day Gou will recover...