An assault on a peaceful city of technology by the evil Doctor Man and the Neo Empire Gear awakens an ancient robot, who chooses five humans to awaken into becoming Bioman to face the mechanical invaders.
Doctor Man sends Farrah and Psygorn to pursue Mika Koizumi about Bioman, even though she had quit the team while the other members try to win her back onto their side.
When Bio Robo becomes unexpectedly damaged during a battle with a Mecha-Gigan, Shirou tries to get a part needed for repair only to have the powerful Monster standing in his way.
Using Shirou's animal informants, Bioman discovers a Gear plot to replace humans with exploding mecha-humans to sabotage a super-energy plant.
In order to discourage people from indulging in a rain of coins created by an invisible Mecha-Gigan controlled by Monster, Shingo decides to become a bad criminal to get the means to stop it.
Mika's pursuit of a lead when a Mecha-Gigan crash lands near a mountain leads her into a confrontation with Farah over a plot connected with a trap by Gear to stop Bio Robo.
When Peebo discovers a letter from a friend from Bio, it inspires Doctor Man to start a plot involving making the robot believe that his friend has returned after 500 years.
As Peebo is forced to give up Bioman's secrets to Gear, the team rescues him as they decide to discover the harsh truth about Joy's ultimate fate.
Ryuuta becomes trapped within the dimension of a supercomputer by twin girl Mecha-Humans being used to capture children for Gear.
Doctor Man develops a gun devised of Anti-Bio Particles to destroy the Bio Particles within the Bioman, forcing Mika to make a move that may ultimately prove to be fatal!
After the passing of their teammate, Bioman search for a new Yellow4, all while they're pursued by a mischievous archer who doesn't realize what she's getting into.
Shingo begins to doubt himself when he believes that a Mecha-Human was actually the father of a boy he was trying to save.
Jun tries to figure a way to defeat Gear's newest upgrade on her own while the captain of the Olympic archery team tracks her down to find out what happened to her.
When Doctor Man abandons a new Canth-controlling super-computer that develops emotions, Hikaru tries to win it over with the concepts of love and empathy.
After being accused by Jun of not doing enough to stop a fungus being distributed by Gear, Hikaru puts it upon herself to find the means to stop their infection plans.
Jun must reach a device that will cause a massive volcanic explosion in 6 hours time, but is distracted by Farah in preventing her from reaching that goal quickly.
Doctor Man orders the abduction of a boy related to Urashima Taro, in hopes of using his ancestor's memory to find the treasures of the undersea utopia.
Shingo encounters a girl who has strange visions of a Mecha-Gigan attacking her town associated with a stone that gives her amazing gifts.
Doctor Man adds his 17-year old son to Gear as its new commander, with a cruelty that Ryuta believes can be stopped.
As the Bioman try to figure out how to deal with Prince and his Grotes Canth, Ryuta tries to discover how to relate his own experiences in hopes of dealing with Doctor Man's son.
A Mecha-Human photographer set up by Monster takes control of an investigating Hikaru, forcing Jun to pick up where she left off in order to save her and discover the plan.
When Ryuta gets involved in returning a gold statue to its original owner, it becomes complicated when Farah sends out a Ryuta mecha-human to steal gold for Gear.
Bioman must protect a runaway girl who ends up with a gemstone required by Gear to perfect their new super-weapon for causing global chaos.
Shingo tries to protect the flowers of two children after Farah and a Mecha-Gigan transform a field they cultivated for sale into bombs set to explode.
Bioman must rescue two boys who possess an ancient treasure map that leads to Biobase, making them targeted by Gear.
Shuichi Kageyama, a boy looking for his family, is attacked by Gear's forces as Doctor Man tries to confirm that he is actually his true long-lost son!
As Doctor Man continues to pursue his son to join him, Shuichi receives a mysterious contact from his mother that leads to the revelation to him and Bioman of the truth regarding Gear's leader.
Hikaru and Jun become trapped in a seaside town conquered by an army of mechanical spiders that control the populace.
Realizing the trouble of Gear being ruled by a human, the Big Three decide to assassinate Doctor Man, leading to a loyal Mechaclone to try and reach a weapon in hopes of dealing with them.
Trying to find a boy's lost brother, Ryuta discovers a Gear plot to suck Tokyo into multiple simultaneous black-hole bombs!
Shirou becomes the fake fiance of a swordmaker's daughter in order to prevent Monster from obtaining a sword for Doctor Man's final Mecha-Gigan.
The Bioman face the Beastnoids in a showdown as a comet that interferes with their powers passes Earth, all while Doctor Man decides to unveil his new secret weapon.
As Bioman works on a new finisher for Bio Robo, Jun tries to help out a girl whose foot is run over by a car controlled by an upgraded Psygorn.
As Bioman tries to focus to create a more powerful finishing move, Shingo returns to his old high school in hopes of finishing a challenge that may help the team.
While working on completing the Super Electron preparations, Peebo gets caught in an explosion and loses its memory as it encounters a boy who is trying to encounter aliens.
When Bioman heads to the mountains to investigate strange meteors that interfere with their Super-Electronic Brains, they meet a weird man who appears powerful enough to start thinking he's their sixth member!
When Shota discovers he can't become a member of Bioman, he unknowingly takes up an offer by Farrah to become their Magne Warrior, leading to him become an enemy of his friends!
A robotic warrior from the war that destroyed Bio arrives on Earth, attacking both Bioman and Gear as he continues his mission to eradicate all Bio Particles in existence!
As Silva searches for his missing mecha Balzion, Peebo decides to confront the enemy Bio robot in hopes of trying to take it down before it takes down Bioman.
After becoming hurt from a Silva attack, Hikaru must rush to the aid of her teammates when Bioman and the Bio Hunter become trapped within a ploy set up by Mason.
After Monster and Zyuoh steals Bio Turbo from Shingo when he tries to show it off for a sick boy, he and Ryuuta take the Bio Machines in order to pursue them.
In order to stop Gear's plot of causing mass hypnosis using a special ring device controlled by Meltzer, Hikaru travels into the dreams of a hypnotised girl to discover how to defeat them.
When Monster's attack on a dam damages a nature preserve for birds, Shirou decides to crush Gear's desires in order to protect the animals living there.
When Bioman encounter a seemingly immortal Neo Mecha Gigan, they must discover the secret of its power associated with a female Mecha Human who lands in the hands of Shuichi!
Bioman and Shuichi try to protect the Mecha Human Miki from the clutches of Gear, even with her as the possible key to stopping the invincible Satan Megas.
When Jun is unexpectedly separated due to a clash of Gear and Silva's weapons, Doctor Man takes advantage by forcing a micro bomb onto Yellow4 to destroy Bio Robo.
When Ryuuta discovers a plot by Monster to turn Tokyo into a jungle with specially-made footballs, he and Bioman try to escape their trap-filled city with their means to accomplish this goal.
As the Biomen tries to assist Professor Shibata on furthering his Conscious Circuit research, they unexpectedly discover Balzion's possible hiding place as Shirou discovers the surprising truth about the mysterious scientist.
With the location of Balzion finally found, Bioman and Professor Shibata attempt to prevent both Gear and Silva from capturing the Anti-Bio mecha for either side.
With both Silva and Balzion in Gear's hands, Bioman faces a relentless, hopeless assault until they gain the hope from an ally to keep going in order to defeat this threat.
Bioman head to Antarctica in order to save Professor Shibata and stop Doctor Man, while Silva makes a final push in order to reclaim his mecha Balzion from the mad scientist.
Doctor Man uses all of his acquired knowledge and technology to perform a final attack on Bioman, unknowing of a familiar presence who decides one final time to try and save what remains of Gear's leader.
