The Dimensional Beasts (次元獣, Jigenjū) are monsters born through the fusion of a Dimensional Bug (次元虫, Jigenmushi) parasite, which assimulates with any material it comes in contact with. The resulting creature would often possess supernatural powers and / or weapons reminiscent of the object. Even if the Beast is destroyed, if the Dimensional Bug survives, it can revive and enlarge it.
Dimensional Bug Mother (次元虫 (母), Jigenmushi Haha, 1-2): An alien monster sent to Earth by Back Dimensional Count Radiguet to drain people of their lifeforce with her tongue and convert into into energy for her babies in her abdomen, the Dimensional Bugs. She was the first opponent the Jetman fought at half-strength, mortally wounded by Red Hawk before Radiguet saves her. After detaching herself from her egg sack, the Mother is sent to attack the Jetman, only to be destroyed by all five.
Fighter Jigen (ファイタージゲン, Faitājigen, 2): This giant monster was originally Chokan's jet that she used to search for the two remaining Jetman but Radiguet interferes with the mission and plants a Dimensional Bug on the jet, starting its transformation into a monster. Though it tried to devour Chokan inside the cockpit, she managed to break free and parachute off the jet. It later went against the Jet Hawk in a dogfight before it grabs Gai Yuuki to use as a hostage. But once Gai is freed and saved, the Fighter crashes and assume full monster form, able to fire orbs from its mouth. However, Red Hawk manages to destroy Fighter Jigen by shooting at the exposed gas pipe.
Faucet Jigen (ジャグチジゲン, Jaguchijigen, 3,27): Originally a faucet implanted with Tran's Dimensional Bug, this monster uses its pipes to wrap around its victims' necks, strangling them. Faucet Jigen later attacks Ryuu while he was trying to convince Gai to join their group as the others come to his aid, getting all four in a corner until Gai returns. After being thrashed by Black Condor, Faucet Jigen is destroyed by the Jetmen.
Road Jigen (ロードジゲン, Rōdojigen, 4-5): Originally a traffic light infused with Radiguet's Dimensional Bug on its thigh, this monster caused trouble by disrupting the traffic from traffic light malfunction to ripping the road. Though it overpowered the Jetman, Road Jigen is defeated once White Swan arrives at the nick of time. But once enlarged, Road is wounded during the fight with the Jet Machines. Once fully healed, Road Jigen resumes its attack and was the first monster destroyed by the Icarus Haken.
House Jigen (ハウスジゲン, Hausujigen, 6): Originally a hotel mansion infused with Radiguet's Dimensional Bug on its forehead, this monster managed to devour many people before the Jetmen meddled in its feeding affairs, forcing House Jigen to reveal itself and attack the city. This was the first monster destroyed by the Jet Icarus.
Mirror Jigen (カガミジゲン, Kagamijigen, 7): Originally a mirror infused with Maria's Dimensional Bug on its right breast, this monster can enter any mirror, taking advantage of humans' vanity to trap them in the Mirror World within its body should they look into their reflections, using them as hostages. The Jetman were at a disadvantage at first until Ryuu's grandmother uses her mirror to deflect the beam and trap Maria in her own monster, forced to release all its hostages. After the Jetman use a physical attack to shatter the monster's mirror chest, this monster was shattered by the Bird Bomber. Though regenerated by its Dimensional Bug, Mirror Jigen was destroyed by the Jet Icarus.
Diamond Jigen (ダイヤジゲン, Daiyajigen, 8,27): The result of Maria's Dimensional Bug assimulating into the Bloody Diamond, a 20 billion yen jewel said to be cursed, Diamond Jigen is used to inflict people with insane greed-filled rage. Once in full monster form, Diamond Jigen uses its power to turn Ako Hayasaka into a crazed psycho, forcing the male members of the team to attack the monster without her and Kaori, who manages to snap Ako out of it with every piece of jewelry she manages to buy with her family's fortune. Once the female members arrives, the Jetman use the Icarus Haken's Jet Phoenix to crack Diamond Jigen, breaking its curse.
Fashion Jigen (ファッションジゲン, Fasshonjigen, 9): Originally a sewing machine infused with Tran's Dimensional Bug on his left shoulder, Fashion Jigen can create Vyram Fashion clothing that can force people into acting according to the nature of the attire. When this monster uses its Vyram Fashion to turn Satsuki into a sniper, Raita Ooishi manages to free his childhood friend before personally defeating this monster with his boulder. Though it was enlarged, Fashion Jigen is destroyed by the Jet Icarus.
Noodle Jigen (ヌードルジゲン, Nūdorujigen, 10,27): Originally a Ramen bowl infused with Tran's Dimensional Bug, this monster assumes the guise of God Ramen (ゴッドラーメン, Goddo Ramen) to trick Ako's classmate, Tatsuta, into creating the Cheerful Ako-Chan Ramen using his special noodles, which would make any who eat it aggressively impatient with superhuman strength after hearing Noodle Jigen play his hypnotic flute. Once Tasuta learns the truth, this monster attempts to kill him when Ako arrives to aid her friend. Though the monster overpowers her, Tatsuta uses Noodle Jigen's dependence on hot water against him, holding him off until the Jetman arrive with an eager Yellow Owl, having ate the ramen prior, and Blue Swallow leading the attack. Once Jet Icarus is formed, it destroys the monster and breaks his spell.
Jihanki Jigen (ジハンキジゲン, Jihankijigen, 11): Originally a Gym vending machine infused with Grey's Dimensional Bug on his right breast armor, this monster can execute his Coin Bomb and Can Bomb attacks. Using his basis as a guise, he gets the Jetman into drinking his juice that influences a flawed part of the drinker's subconscious to cause a personality reversal whenever they hiccup. He later attacks Raita, with the others arriving to his aid. Confident that the Jetmen have become useless in battle, Jihanki Jigen goes on the attack with only Gai able to fight him as his personality flaw is being a good guy. With Ryuu lazily supporting him, Gai managed to restore the others to normal as they all kill Jihanki Jigen with the Bird Bomber. Though revived by the Dimensional Bug, Jihanki Jigen is easily destroyed by Jet Icarus.
Bus Jigen (バスジゲン, Basujigen, 12): Originally a public transportation bus infused with Tran's Dimensional Bug, Bus Jigen uses his guise to take people and disgust them one by one whenever in a dark place, leaving only foaming remnants of its prey. Kaori and Raita happen to be on the bus, believing that someone on the bus was killing. By the truth is after the driver, revealed to be a fugitive named Ota Kenchi, is digested. By then, the bus begins to assume its true giant form as the passengers escape. White Swan risks her life for Yellow Owl to get the others to run off before the others arrive in the Jet Machines. Forming Jet Icarus, the Jetmen battle Bus Jigen before using the Birdonic Saber to destroy it.
Camera Jigen (カメラジゲン, Kamerajigen, 13-14): Originally a camera infused with Maria's Dimensional Bug, Camera Jigen uses his Lens Beam on whomever he takes a picture of would be transported into Maria's photo album. Once able to assume his natural form, he is able to use the explosive Flash Beam and shoot a mist from his left forearm. Camera Jigen later supports Maria in attacking Gai and Kaori before the other Jetmen arrive. However, Camera Jigen captures White Swan before targeting every young woman in the city. After they find his weakness, exposed while using his Lens Beam, the Jetmen attempt to hit it when Grey arrives to support Camera Jigen, with Raita and Ako taken as a result. By the time Gai is captured, Ryuu completes the Fire Bazooka modification and uses it free everyone Camera Jigen took before the Jetmen use the Fire Bazooka to kill the monster. But though revealed by his Dimensional Bug, Camera Jigen is easily destroyed the Jet Phoenix.
Voice Jigen (ボイスジゲン, Boisujigen, 15): Originally a megaphone infused with Maria's Dimensional Bug, Voice Jigen feeds on women's voices, giving them deep-sounding ones in exchange, as part of Maria's plan to use the stolen voices to make Voice Jigen into a weapon of mass destruction with his Super Destructive Sound waves. Among the victims was Kyoko, with Ako going after him at the cost of her own voice and unknowningly exposing herself as a Jetman. But once the team learns that Voice Jigen targets only women, Raita pretends to be a geisha to trick the monster into feeding on his voice, losing all the voices he stole as a result. With Kyoto's support, Blue Swallow defeats Voice Jigen before he is killed by the Fire Bazooka. Though revived by his Dimensional Bug, Voice Jigen is destroyed by Jet Icarus when Blue Swallow uses the Birdonic Saber.
Kami Jigen (カミジゲン, Kamijigen, 16, 27): Originally an origami infused with Tran's Dimensional Bug on its left shoulder, Kami Jigen has the power to bring images and sheets of paper to life and have them attack people. Stopping the Jetmen from assuming fighting form, Kami Jigen overpowers them until he runs off as he couldn't tolerate the music of the ocarina played by one of the images he brought to life, a painting by artist Shuichiro Mabuki of his late daughter Shizuko. Because she was created with passion, "Shizuko" was immune to Kamijigen's control as it is sent after her upon being considered a threat by Tran. But Ryuu comes to "Shizuko"'s aid, with the others covering their escape. After leaving "Shizuko" by her father's bedside, Red Hawk returns to the fight with Kami Jigen regaining the upper hand until Shizuko holds the monster at bay with her music. But when he killed her to stop the music, an enraged Red Hawk goes wild on Kami Jigen before using the Fire Bazooka to kill him. Though revived by his Dimensional Bug, Kami Jigen is destroyed by Jet Icarus.
Uranai Jigen (ウラナイジゲン, Uranaijigen, 19): Originally a fortune telling machine infused with Maria's Dimensional Bug on her left breast, Uranai Jigen has the power of illusion and uses tarot cards as her weapon. Posing as a fortune teller named Lilika Loui Inoue, Uranai Jigen targets Kaori with coincidental predictions that drive her crazy before giving her a tragic illusion of her future where she is killed by Maria at the Bay Bridge. She then traps the other Jetman in another dimension where she uses illusions to torture them until using the Guillotine Tarot Card attack on them. But Kaori stops her before the attack is carried out, overcoming her fear of the future. White Swan battles Urana Jigen before the Jetmen use the Fire Bazzooka to kill the monster and destroy her Dimensional Bug in the process.
Sojiki Jigen (ソウジキジゲン, Sōjikijigen, 20): Originally a vacuum infused with Tran's Dimensional Bug on the right side of his head, Sojiki Jigen can use his vacuum hose to suck or blow or as a whip. He is sent to suck the love out of brides order to keep humans from repopulating. One such victim was Sakiko, the older sister of Michiru who pursue the monster to get to the bottom of it and meets Gai, who eventually believes her. Though he overpowered the Jetmen, they trap him with a fake wedding between Gai and Ako. But Michiru blows the deception with Sojiki Jigen stealing her love while running off. This in turn infuriates Gai, finding Sojiki Jigen as Black Condor kills him with extreme prejudice. Though revived by his Dimensional Bug, Sojiki Jigen is destroyed by Jet Icarus with the Icarus Crusher, restoring his victims to normal.
Gomi Jigen (ゴミジゲン, Gomijigen, 21): Originally a pile of garbage infused with Maria's Dimensional Bug after Tran took it from her, Gomi Jigen's will is provided by Ako's teddy bear Poo-tan. Though a good natured monster with the power to restore things to good condition, Gomi Jigen is the victim of prejudice before he found by Maria who attempts to discipline him before Ako arrives. Recognizing Ako as his "mama", Gomi Jigen follows Ako everywhere she goes before she leaves him at the dump so he can make a living ingesting garbage. However, after an attempt on his life by corporate goons whom he offended, Gomi Jigen is found by Maria who turns him into a giant rage-filled monster. After Ako attempts to reason, she joins the other Jetman in fighting Gomi Jigen as Jet Icarus. But when Blue Swallow saves a little girl, Gomi Jigen regains himself and returns to his normal size to save Blue Swallow. However, Maria kill Gomi Jigen with a saddened Ako later making a memorial to him.
Dryer Jigen(ドライヤージゲン Doraiyājigen?) (28): Originally a dryer infused with Tran's Dimensional Bug, Dryer Jigen calls himself the "Founding Dimensional Beast." In response to being called outdated, this monster unsuccessfully tries to prove itself by gathering madcap Grinams who share his plight to take out the Jetmen with. However, when it was about to finish them off, this monster is revealed to be a nice guy to everyone's shock as his Grinams ditch it. After an attempt to take two school girls hostage only to end up coming to terms with his goodness, this monster helps the Jetmen before leaving the scene at their request. Soon after, he takes up a job as an apprentice in a barbershop. Dryer Jigen was the only Dimensional Monster in this series to not be destroyed at all.
Maria modified the Dimensional Bugs into Bio Dimensional Bugs (バイオ次元獣, Baio Jigenmushi), which give raise to Bio Dimensional Beasts (バイオ次元獣, Baio Jigenjū), which not only possess supernatural powers and / or weapons reminiscent of the object, but also influenced by the animal DNA integrated into each Bio Dimensional Bug.
Light Armadillo(ライトアルマジロ Raitoarumajiro?) (25): The result of Maria's Bio Dimensional Bug imbued with armadillo DNA fused with a Baseball field's light post, this monster can roll itself into a ball while using its light bring shadows to life while the target becomes weakened over time as their life force transfers into the shadow. When attacked by the Jetmen minus Gai, it creates the Shadow Jetman(影ジェットマン Kage Jettoman?) as its enforcers as Maria creates an artificial light for the shadows to thrive in until their hosts all die. Canceling Maria's artificial light, Gai joins his team in defeating this monster with the Fire Bazooka. This was the first monster to be destroyed with Jet Garuda.
Jiku Mammoth(ジクウマンモス Jikūmanmosu?) (26): The result of Grey's Bio Dimensional bug imbued with mammoth DNA fused with a time piece, this monster calls out the Jetmen before using its Time Slip Beam on them. But Yellow Owl's attack causes them all to end up in prehistoric times. After enough jewels to regain his full power, This monster enlarges itself and overpowers the Jetmen they manage to force the monster back to the present where it was destroyed by the Great Icarus.
'Armor 'Snake(ヨロイスネーク Yoroisunēku?) (29): Created by Radiguet with a Bio Dimensional Big infused with snake-DNA integrated with a suit of samurai armor, this monster was sent to take over Lu's body in order to use her Beserkian powers. However, it consumes Duran instead and has him try to kill Lu until the Jetman blast the snake decoration, causing the monster to break into pieces and free Duran from its influence. This monster was not enlarged.
Adhesive Cockroach(粘着ゴキブリ Nenchakugokiburi?) (33): The result of Maria's Bio Dimensional Bug with cockroach DNA fusing unto a glue bottle, the super-fast monster was motivated by his kind's persecution by humans in his attacks of sticking humans with his super-strong glue. This monster temporarily disabled Jet Striker and surviving the Bird Bomber. This monster became the first to be taken down by the completed Beak Smashers and destroyed by the Smash Bombers. This monster was not enlarged.
Toxic Gas Rat(毒ガスネズミ Dokugasunezumi?) (35): The result of Radiguet's Bio Dimensional Bug with rat DNA fusing unto a vat of toxic waste, this monster is used to spread deadly fumes across the city. Losing its arm during the first fight, this monster ate enough toxic waste to regenerate its forearm before attacking Ako, leaving her temporarily blind. After being defeated by Blue Swallow as she barely regains her sight and then blasted by the Smash Bomber, the enlarged monster was destroyed by Jet Icarus through the Tetra Buster.
'Ant 'Bazooka(アリバズーカ Aribazūka?) (36): The result of Tran's Bio Dimensional Bug with ant DNA fusing unto a bazooka, Ant Bazooka assumes the form of a swarm of ants that enter humans and turn them unto ravenous gluttons under Tran's control with Kaori among them. However, reforming on Tran's command and enlarging, this monster was destroyed by Jet Garuda.
'Torpedo 'Piranha(ギョライピラニア Gyoraipirania?) (37): The result of Radiguet's Bio Dimensional Bug with piranha DNA fusing unto a torpedo, this monster was sent by Radiguet in an attempt to kill Tranza and Ryu. However, the other Jetmen arrrive and managed to destroy it by attacking the head on its stomach before it fired its trademark torpedo attack. This monster was not enlarged.
Hammer Chameleon(ハンマーカメレオン Hanmākamereon?) (38): A result of Tranza's Bio Dimensional Bug with chameleon DNA fusing with a hammer, this monster was deployed to retieve Laser Lizard's Bio Dimensional Bug. Able to turn invisible, this monster loses its hammer arm before it was destroyed by the Smash Bomber as it attempts to escape. However, this monster was revived when Laser Tokage's Bio Dimensinal Bug thrawed and fuses unto the original's hammer. This monster was enlarged by Tranza and was destroyed by Jet Garuda.
Sniper Cat(スナイパーキャット Sunaipākyatto?) (39): A result of Grey's Bio Dimensional Bug with cat DNA fusing with firearms, this monster serves his master in turning all the Jetmen minus Black Condor into chess pieces. This monster later appears to gun down Gai should he lose to Grey in a casino match, enlarging after his master loses before being destroyed by Jet Garuda with the Tetra Buster.
Meteor BEM(隕石ベム Insekibemu?) (40-41): Created by Radiguet's Bio Dimensional Bug fusing in a meteor made of an anti-Birdronic metal, this monster weakens the Jetmen with its very presence and nearly kill them were it not for the sudden appearance of Neo-Jetmen. When Metor BEM returns as a giant, it defeats the Neo-Jetmen in Jet Icarus until the Jetman arrive before Meteor BEM completely negates their Birdonic energies as the Tetra Boy comes to their aid. Though seemingly destroyed by Jet Garuda with the Tetra Bomber, Tranza remove this monster's core and sneaked it into Jet Icarus before it regenerates into a new Meteor BEM which begins smashing the Sky Camp while overpowering the Neo Jetman. With a boost from the Neo-Jetmens' power, the Jetman regain their powers and they finally destroy this monster with the Great Icarus.
'Leech' Drill(ヒルドリル Hirudoriru?) (43): Bent on defeating the Jetmen before Tranza can with Veronica, Radiguet integrated a drill with Bio Dimensional Bug infused with Leech DNA. Using a bouquet of roses to sneak into Chokan's body, this monster takes control of her body in order to snare the Jetmen into a trap while sabotaging their arsenal. Once the Jetmen realized something's up, they are forced to restrain Chokan as manage to duplicate the monster's cell reduction energy to use Jet Icarus to force this monster out within the 3 minute time limit. After managing to make it out in time via the tear duct, this monster managed to completely render Jet Icarus powerless. However, Chokan pilots Jet Garuda to get pay back as she destroys the monster.
Destruction Beast Semimaru(破壊獣セミマル Hakaijū Semimaru?) (18-24): The ultimate beast of destruction; an insectoid who is legendary for its destructive power. Juuza acquired such a monster and brought it to Earth while as an egg, feeding it enough human suffering to hatch. Though she succeeds in her plan, Juuza is killed by Radiguet who raises Semimaru from its green larval form to a red armored human-sized version before it pupates. Once it emerges, the matured winged Semimaru enlarges itself as it goes on the rampage across the city while defeating Jet Icarus until the Bird Garuda intervenes and freezes the monster. However, once the monster breaks out, it defeats Jet Garuda before leaving to heal its wounds. But Semimaru meets its end fighting the newly formed Great Icarus.
Majin Mu(魔神ムー Majin Mū?) (30): A servant of Ramon and Gorg, Mu was put to sleep along with his two masters since Taiko era. Accidentally released from his urn by two lost travelers, Mu goes to find an ideal warrior to use in a blood sacrifice to free his masters. Arriving to the scene of the Jetman's fight with Radigam, Mu attacks them to pick out a suitable sacrifice and abducts Kaori to begin the ritual. However, the Jetman intervene and battle Mu as they use the Fire Bazooka on him which he endured. Finding his masters revived, Mu was killed by Gorg for being useless.
Majin Ramon and Gorg(魔神ラモンとゴーグ Majin Ramon to Gōgu?) (30-32): The natural enemies of humanity, who turn humans into fruit for consummation. Sealed during the Taiko Era, they could only be released by the blood of a warrior, with Radiguet giving them his in return for their loyalty. However, the two have no interest in serving someone who harms humans as they start to feed until the Jetman intervene. Enlarging, Gorg battles Jet Icarus and Jet Garuda until the Tetra Boy arrives and defeat the demon. With Gorg mortally wounded by Jet Icarus with the Tetra Buster, Ramon attempts to absorb him. But Radiguet and Grey spirit away the dying Gorg and seed him with Bio-Dimensional Bugs before Ramon finds him, succeeding in gaining control of the fused demon lord. But even with Gorg's power augmenting his own, Ramon is defeated by the Jetman and then destroyed by the Hyper-Haken.
Strange Dimensional Lifeform Jigoku Medusa(異次元生命体ジゴクメドゥーサ Kaijigen Seimeitai Jigokumedūsa?) (34): An internal defense mechanism designed to hunt down any intruders, it attacks Ryu when he infiltrates the Vylock. Enlarging to stop the Great Icarus from taking out the Dimensional Transfer Machine, it siphons the giant robot's energies to become a living bomb to take out the Jetman until the Tetra Boy intervenes and holds the monster long enough for the Great Icarus to destroy Jikgoku Medusa.
Trial Manufacture Robot G2(試作ロボットG2 Shitsuku Robotto Jītsū?) (42): A yellow robot created by Tranza as a predecessor to building a means to counter the Jetman mecha, G2 suddenly malfunctioned and was used as a test dummy by the Grinams while developing a child-like mind. Escaping to Earth, G2 finds itself in the middle of Grey and Maria's hunt for Gai and Kaori. After being repaired by Grey, G2 attempts to win his love. To that end, G2 kidnaps Maria to bring to Grey. Damaged protecting Maria from a landslide, and damaged even more while trying to protect Grey from Jet Bazooka, G2 is abandoned as it plays Maria's tune before self-destructing.
Majin Robot Veronica(魔神ロボ ベロニカ Majinrobo Beronika?) (43-45): The ultimate giant robot built by Tranza, it required human life energy as a power source. Upon appearing on Earth, piloted by Tranza and the other Vyram officers, Veronica wreaks havoc on the city as it defeats Jet Icarus and Jet Garuda while keeping them from forming the Great Icarus. But before Veronica could finish them off, it is damaged as a result of Radiguet's attempt to take the controls from Tranza to deal the final blow. After Grey finishes repairs, Veronica resumes its attack as the Tetra Boy arrives to hold the robot off until the Great Icarus arrives. However, Veronica damages the giant robot after its power source is revealed. By the time Veronica returns, now powered by three of the Jetman, it overpowers the Great Icarus until Radiguet's sabotage manifests. With Grey piloting Veronica as Tranza deals with Red Hawk after doing away with Radiguet, who completely drains Veronica's power as the Jetman fall back with the other captives to the Great Icarus, which uses its Bird Maser in conjunction with the Tetra Boy to destroy Veronica.
Tomato Great King (トマト大王, Tomato Daiō, 46): The result of an Outer Dimensional entity called Metamol assuming the form of a nightmare from Raita's childhood when he was afraid of tomatoes, the Tomato Great King possesses the power to turn people into tomato-headed freaks. Because it feeds on Raita's fear, this monster overpowers the Jetman as Tranza enlarges it. However, once Raita manages to overcome his childhood fear, this monster loses his power until he is reduced to a headless version of himself. This monster was destroyed by Jet Garuda.