MADGONE

The second main antagonist of the series, and the one who serves the longest term of them all, Madgone arrives immediately after Antigone kicks the bucket and sets about to destroy Jumborg Ace. Armed with a gas that can turn humans and animals crazy, as well as several powerful monsters and robots, Madgone ups the ante considerably, pushing Jumborg Ace and PAT to the limit.
While I don’t find him as fun or memorable as Antigone myself, I think Madgone is a great opponent for a majority of the show, and he really earns the title of arch-nemesis, even if his superiors will show up down the line. Many of Jumborg’s toughest battles, as well as even a few defeats will come at the hands of this guy, which is pretty impressive for a toku villain and his MOTW.
Madgone’s design is a really creative one by Yonetani, being inspired by electrode coils and Raijin, a god of thunder from the Shinto faith. The horns also form a Y-shaped pattern, based on Yonetani’s initials.
It’s a common misconception that Madgone is Antigone’s brother, due to the latter calling the former that as he dies, but Yonetani denies the two having any blood ties.
MAD SATAN

For his first plan, Madgone unleashes a kind of plant known as the Mad Flower. Thriving off of the pollution in an industrial area, the plants suck the blood of their victims, transforming them into mummies. When PAT catches on, Madgone combines the flowers into the monster Mad Satan.
The thought of a beautiful, but deadly flower that thrives off of pollution feels exactly like something out of the playbook of Dr. Gori from Spectreman, but I suppose why I like it. It’s a great juxtaposition of beauty and ugliness that not many pollution themed monsters tend to go for, and I love how the design just is so scuzzy. One particular feature I love is the flowers on the head, which give Mad Satan a fly-like appearance, perfectly fitting for this monster.
MIGHTY GROSS

After Madgone brainwashes a man into attacking Naoki when he’s piloting the Cessna, Madgone sends Mighty Gross to attack the PAT base, knowing full well that Jumborg Ace can’t fly in and save the day.
Mighty Gross is another really cool sauropod kaiju from 70’s era Tsuburaya. Based on a brontosaurus, what makes Mighty Gross stand out is the fact that those barnacle inspired growths on his body are suckers that can suck in Jumborg’s limbs! Yuck!
DEMONSTAR

Disguised as a witch with a haunting voice, Demonstar guards a valley where Madgone is building himself a secret Earth base, Demonstar takes advantage of the local villagers’ superstitions to prevent anyone from coming across the currently constructed stronghold. The idea of a monster disguised as a human to guard the villain’s secret base feels much more like a plot out of Mirrorman.

Fittingly enough, Demonstar’s monster form looks like something that would be seen in the latter half of Mirrorman. It’s a pretty good design though, being based off of frilled lizards, and feels appropriately “witchy”, even if it’s not super obvious at first glance, and the orange and red frill adds a nice splash of color to the body’s otherwise cold color scheme. The witch disguise itself was meant to emulate the Evil Queen from Disney’s Snow White appropriately enough.
FREEZER KILLER

A powerful monster with freezing abilities, Freezer Killer is a riff on Pestar from the original Ultraman design wise, and honestly doesn’t look too bad. He maintains a powerful presence in his episode, as Kaine, the son of the Emeraldian that gave Naoki Jumborg Ace not only warns him of the monster’s arrival, but even comes to Earth himself and sacrifices himself to keep Jumborg Ace safe from the monster’s deadly freezing abilities. All in all, a solid and sadly overlooked boss monster.
ANTRON

Sort of a redux of his plan with Demonstar about two episodes ago, Madgone attempts another secret base located in a valley location with a monster, Antron, guarding it.

Unlike Demonstar, Antron doesn’t have one human disguise, but rather seven, as the creature can separate into a group of humans who make a human pyramid when the need arises to become Antron again.
Antron’s ability to separate into numerous human guises brings to mind monsters like Unitang and Pairmonsking from Ultraman Ace and Mirrorman respectively, although Antron and his abilities were inspired by King Joe rather. The design by Yonetani is a pretty decent one, combining a macaw’s head on a crustacean inspired body to make a strange looking monster, and like Antigone’s monsters from before, he’s armed to the teeth with missile launchers in his hands, as well as a detachable sword on his head to do battle with Jumborg Ace with, a deliberate nod to Rubanger King from earlier in the show.
VALENTINE

A bizarre mouse-octopus monster, Valentine steals a hydrogen bomb which Madgone plans to drop onto Tokyo, and very nearly succeeds until Jumborg Ace intervenes.
Valentine is a really odd one, although he always struck me as one of the show’s most iconic monsters, probably because a mouse-octopus hybrid is a really inspired idea for a kaiju. Taking his name from the infamous St. Valentine’s Day Massacre (hence his red color), he’s certainly striking with all those tentacles and suckers, something that Yonetani intended to have beams fire from, but was left out in the final episode, something he regrets. The fact he’s a flying monster rather than being some kind of aquatic beast just adds to the strangeness. He’s just emblematic of how weird tokusatsu TV monsters can get.
DUMP KONG

Madgone’s next attempt in sowing chaos involves sending down some Growth aliens to possess several junker cars to cause several traffic accidents. Madgone then combines the Growth aliens into a junker slated for the junkyard, creating the monster Dump Kong. However, Jumborg Ace is convinced by the child who’s father owned the Dump Truck to spare the monster, and the robot hero uses his Emerald Beam to restore the truck back to normal and vanquishing the Growth aliens.
Goofy name aside, Dump Kong is a nice looking robot monster, being made of various different car parts makes him look very unique amongst the monsters of Jumborg Ace, and the asymmetrical design combined with the dirty gold, grey and black color scheme make it a nice, eye-catching monster. One notable thing about the design is that the license plate number is different than the truck’s used in the episode, and was actually the last four digits of Yonetani’s phone number!
WUTAN

When PAT sends out a missile to the Emerald home world due to a Growth base being spotted there, Jumborg Ace flies out to try and prevent the destruction of the Emerald’s planet, only for Madgone to unleash Wutan, a kaiju with the ability to summon illusions of past monsters Jumborg Ace has defeated. With Jumborg Ace distracted by the “ghosts” of his previous opponents, Wutan lands on Earth to go on a rampage.
Wutan has always been one of the more memorable monsters from this show, and I think it’s due in part with the wonderful design by Yonetani, which takes inspiration not only from orangutans, but also Garamon from Ultra Q. Aside from his ability to conjure illusions of dead monsters, Wutan’s got some other powers such as finger missiles, rolling into a ball, but the most memorable weapon in his arsenal are his cheeks, which inflate and can be fired off as bombs! You can see the effect in the photograph above, something they achieved using balloons!