The Dark Empire Yodonheim is an evil empire of dark beings under the command of Emperor Yodon that conquered Crystalia with their Yodon Army invasion force before setting their sights on Earth. Their main objective is to destroy everything that is beautiful in the universe. After Emperor Yodon's death, Carantula reorganizes Yodonheim and maintains a good relationship with Earth and Crystalia.
Emperor Yodon is the mysterious leader of Yodonheim who possesses two additional personalities. He was originally a conglomerate of serpents born from the embodiment of corruption who rose to power after creating his own Jamen and devouring his defeated opponents, assimilating their powers while increasing in size. Yodon subconsciously created Yodonna and Shadon to use them as protective guises so he can safely travel to other worlds not consumed in darkness. Years prior to the series, he corrupted a young Galza into resenting his kingdom, which eventually led to Crystalia's destruction and Oradin's defeat.
Initially acting from the shadows, Yodon came to Earth as Yodonna to assist his generals in invading Earth before eventually revealing himself. Sometime after Shadon's destruction, Yodon absorbs Galza as a replacement and is seemingly killed by his traitorous general. However, the emperor drops the ruse after Juru reveals the existence of the Kanaema Stones and proceeds to invade Earth to hunt the artifacts and reshape the entire universe to his liking. After being tricked into removing his Jamen, Yodon is ultimately destroyed by a fatal shot to his exposed head from Juru's Kiraful Go Arrow finisher enhanced by the Destoria Kanaema Stone.
Yodon's other selves are represented by a pair of masks, each of which hang off his Jamen and covers his main mask when he takes on their appearance. As his alternate personalities are separate beings unto their own, Yodon can communicate with them through their Yodon Changers. On his own, Emperor Yodon is capable of unleashing a mass of darkness from his body and laying waste to several city blocks. As a conglomerate of darkness, Yodon is incapable of sustaining himself in pristine and beautiful areas without switching to one of his alternate personalities. He can also summon an army of Emperor Guard Bechats to aid him in battle.
Yodonna is an alternate personality of Emperor Yodon who initially believed herself to be his private secretary. She arrives on Earth to support Galza and Carantula due to the Kiramagers' interference in their invasion plans. While Yodonna maintains her loyalty to Yodon, he executes her after she becomes a liability in his fight against the Kiramagers, embracing her demise if it meant Yodon would be victorious.
In her titular web-exclusive series, Yodonna ends up in the Yodon afterlife to await judgment. However, she steals a revival device and returns to Earth in the hopes of possessing the Kiramagers' leader Juru Atsuta and use his life force to revive herself, only to accidentally end up in the body of his girlfriend, Mizuki Kakihara. Yodonna settles for this development, but is forced to protect Kakihara from Yakuza members that the latter's detective brother was investigating. In the process, Yodonna befriends Kakihara and they help each other learn emotions and work on her attitude respectively. As a result of their friendship, Yodonna only siphons enough energy from Kakihara to temporarily sustain her physical form and destroys the revival device. After saving Kakihara from Yakuza leader, Hideki Kujirasaki, Yodonna returns to the Yodon afterlife, but realizes she can revive herself if she learns to love.
She can transform from her human form to her Yodonheim uniform using the Yodon Changer. She is also armed with the Akkanben riding crop that can enhance Yodonheim members at great cost to them or divide whomever she hits into five duplicates of themselves, each of which embody a different personality trait and can merge back at their leisure.
Shadon is an alternate personality of Emperor Yodon's who believes himself to be a hunter and his direct messenger. He is armed with the Croco Rifle sniper rifle and, like Yodonna, is equipped with a Yodon Changer. He is destroyed by Go Kiramai Yellow.
Also known as the "Treacherous Demon General", Galza is a fierce, aggressive Crystalian general armed with the Crush End hook sword. He is Oradin's younger brother, Mabushina's biological uncle, and Takamichi's foster uncle.
Once an idealistic young Crystalian and one of the chosen heroes of his home planet, Galza's mind was corrupted from an early age by Emperor Yodon, causing the former to resent Oradin and everything he cherishes as well as have no memory of his encounter with Yodon. As an adult, Galza believed himself more worthy of becoming king than Oradin due to his stronger Kiramental, with the resulting jealousy and resentment over being denied the throne driving him to side with Yodonheim. He subsequently became general of the Yodon Army, overseeing the attack on Crystalia before tracking Mabushina to Earth. Amidst his battles with the Kiramagers, Galza develops a rivalry with Juru after seeing similarities between him and Oradin as well as cultivate a dark power similar to Kiramental fueled by his negative emotions; which Carantula later calls "Jamental". Following Oradin's revival as Mashin Oradin, Galza hones his Jamental further to compete with his brother's growing powers, obtaining the ability to brainwash the Kiramagers' Mashin into his service.
After Shadon is killed in battle, Galza offers himself to Yodon as a replacement personality in a scheme to take over the latter's body, transforming himself into the more powerful Lord Galza, who is armed with the Gold Chainsword. When Juru breaks into Yodonheim and reveals the Crystalian's forgotten past, Galza realizes he had been manipulated and attempts to atone for his misdeeds, only for Yodon to remove Galza and fatally wound him. Despite this, Galza uses the last of his life force to save Juru, entrusting him with Mashin Jouki before making peace with Oradin and departing to the afterlife.
Also known as the "Dark Masked Magician", Carantula is the Yodon Army's strategist who seeks inspiration from the culture and technology of the planets he invades to develop new methods for conquering them. He is armed with the Yodo Meter spear and is able to create Jamen masks to convert Bechats into Jamenshi and Dark Beasts into Jamen Beasts, storing the dark energy created by the former during their attacks in his staff to summon the latter.
However, after Yodonna splits him into five duplicates and the Kiramagers destroy the one embodying his loyalty to Emperor Yodon, Carantula becomes frustrated by Yodonna's subsequent abuse and bonds with Juru as a fellow artist. The former quits his position in Yodonheim and is almost executed by Yodon, but Galza saves Carantula to help him betray the emperor. Carantula later grants the Kiramagers access to Yodonheim and reclaims the Illusia Kanaema Stone for their final fight against Yodon. After Yodon's death, Carantula takes over leadership of Yodonheim and stops invading other planets.
The Bechats are the Yodon Army's foot soldiers armed with the Numade rakes. With a Jamen, a Bechat can be promoted to a Jamenshi. Through the power of Yodonna, a Bechat can become a zombie-like Hyper Bechats with increased strength, but at the cost of expiring soon after. In the final fight against Emperor Yodon, the dark ruler summons Emperor Guard Bechats as reinforcements.