Introduced as a standout character in the short video "Audrey's Subtlety" by Hagen Toons, Eden introduces an entirely new perspective to the group’s usual roomie dynamics. Eden is typically portrayed as quiet, unassuming, and relatively modest. Wearing a simple oversized hoodie, he serves as a completely clueless and dense target for Audrey's attempts at flirting. True to the video's title, when Audrey tries to drop "subtle" hints, Eden's innocent, slightly oblivious demeanor means the romantic tension completely flies over his head, making him an adorable but frustrating match for her usual direct charm. Rather than working a forward-facing job like Audrey’s cafe gig, Eden leans into a quiet lifestyle. He is comfortable staying out of the intense, fast-paced grind, content to wear comfortable loungewear and focus on his personal space rather than chasing corporate status.Being introduced primarily through his interaction with Audrey, Eden’s social circle is highly low-key. He represents a refreshing change of pace from the absolute chaos that Hannya, Lina, and the other roommates bring to the table. His calm, unsuspecting presence grounds the dynamic, even if it leaves Audrey frantically trying to figure out how to grab his undivided attention.

Introduced as a fresh face expanding the Koji no Bōken universe in the special short "Audrey's Cousin Kardia", Kardia adds a new flavor to the household dynamic. Kardia is designed to be the ultimate tease, carrying a vibe that heavily contrasts with Audrey's easily-irritated nature. She is highly confident, playful, and possesses an incredibly smug, mischievous attitude. She thrives on catching people off guard especially Koji. Unlike Audrey, who can get flustered by things like extreme heat, Kardia stays completely cool, using her alluring charm and expressive body language to effortlessly control whatever room she walks into. Rather than grinding out a structured 9-to-5, Kardia’s role is that of a bold, opportunistic visitor who lives in the moment. When she isn't acting as a model or a lifestyle influencer type, she loves sticking her nose into the household's business, treating her visits less like a family duty and more like a personal playground. Her introduction immediately shakes up the social hierarchy. While she shares a playful, highly competitive family bond with her cousin Audrey, her main target is Koji. She wastes zero time testing his boundaries, generating instant comedic tension with the rest of the household. Her unapologetic, flirty confidence leaves the other girls especially the possessive Hannya scrambling to reclaim the spotlight.

Lina functions on a slightly different wavelength than the core roomies, carrying a bolder, more proactive attitude. Lina does not sit back and let things happen. She is highly self-assured, bold, and fiercely independent.She doesn't tolerate nonsense or being treated like a child. If someone crosses her or slacks off, she has a sharp tongue and a quick fuse, though her anger is usually played for laughs. She is incredibly intelligent and goal-oriented. When the crew needs a practical solution to a chaotic mess, Lina is usually the one laying out the variables to make sure they succeed. Lina holds a more structured and authoritative role compared to the rest of the roomies. She often handles administrative, management, or highly professional tasks where her sharp intellect and low tolerance for failure can be put to use. She is typically the one dealing with schedules, rules, or managing a tight ship.Lina’s social life is defined by tough love. She doesn't hold back her opinions, meaning her social interactions are full of sharp banter and calling out the others when they are slacking off or being overly chaotic. Despite her short fuse, she is deeply integrated into the group because they rely heavily on her to fix their practical real-world problems and keep them grounded.

Maty plays the vital role of the group’s grounding wire, acting as a contrast to both Audrey's easily-irritated nature and Hannya's wild energy. Maty is characterized by her endless patience and sunny outlook. She is typically the most polite, modest, and gentle member of the crew. While her overly relaxed demeanor can sometimes make her look lazy or submissive at first glance, she is actually highly creative and incredibly hardworking when a project needs to get done. Because she rarely gets angry or passes judgment, she often acts as the emotional buffer when Audrey and Hannya start bickering or clashing. Maty is a highly creative freelance digital artist and animator. While the other girls often mistake her incredibly relaxed, quiet demeanor for laziness, she is actually an absolute workhorse when she is locked into her art space drawing or working on commissions.Maty is the absolute sweetheart and peacekeeper of the house. Because she is so laid-back and rarely gets mad, she functions as the ultimate emotional buffer. When Hannya or Audrey start screaming or causing drama, Maty is the comforting, drama-free safe haven everyone vents to.

Hannya is one of the most visually distinct and expressive characters in the main group, easily recognized by her signature demon-mask aesthetic and energetic personality.Unlike the more rigid elements of the group, Hannya is highly spontaneous. She tends to act first and think later, often driving the physical comedy or getting the group into absurd situations. According to character lore, she experiences emotions intensely. She swings between hyper-fixation on her goals, intense bouts of jealousy, and overwhelming excitement very quickly. Despite her aggressive or chaotic outbursts, she is fiercely protective of her friends and possesses a genuinely friendly, clingy sweet side when she isn't being unhinged.Hannya’s professional life is usually fluid, often taking on various bizarre odd jobs, gigs, or matching the chaotic energy of whatever scheme the group is running. However, because of her intense aesthetic and hyper-expressive nature, she is occasionally depicted in roles that allow her to leverage her dramatic flair—or flat-out cause workplace disruptions. She is the ultimate social livewire. Her social circle revolves tightly around Koji, Audrey, and Maty, but she is highly possessive. Her social interactions are fueled by sudden bursts of jealousy, playful teasing, and a desperate need to be the center of attention. She maintains a playful, teasing rivalry with Audrey, yet they frequently hang out as a duo (like going out together for holiday specials).

Audrey is one of the primary original characters from the slice-of-life animated web series Koji no Bōken (Koji's Adventures), created by the Mexican animator and YouTuber Hagen Toons (Hagen Wolfhowl). She is generally depicted as the relaxed, "cool roommate" figure. She handles everyday situations with a relatively calm demeanor compared to some of the more chaotic characters in the cast.While she tries to stay relaxed, she has a low tolerance threshold for specific discomforts. For example, she has a canonical hatred for hot weather and gets easily annoyed or frustrated when the temperature spikes (a central joke in the popular short "Audrey and the Heat"). True to the mature nature of Hagen Toons' animations, Audrey is very comfortable with her sexuality. She has a fun-loving, open attitude toward intimacy, can be quite flirty when she finds someone attractive, and is canonically identified by the community as bisexual. Despite being friendly and sweet at times, she isn't overly formal or ladylike. She has an unrefined, tomboyish edge to her behavior that contrasts with her highly feminine design. She is part of the core four-character dynamic alongside Koji, Hannya, and Maty. She frequently serves as the voice of reason (or at least the most grounded perspective) during their bizarre misadventures.

Azazel is the gestalt form of Set (0018) and the demon Atun.In comparison to Set possessed by Atun, Azazel is even more ruthless, bearing deadly powers and a sadistic demeanor despite his gentle appearance.

Atun is a demon used in the Cyborg Daemon project of Dr. Adams Teufel and one of the main antagonists of the crossover OVA 'Cyborg 009 vs. Devilman'. Atun, like most demons, has a dominating and cruel outlook with a large superiority complex, believing that he is stronger than anyone. He has a history with the demon Amon having a similar reputation as a mighty hero, but Atun wants to prove that he is stronger than him. He is willing to cooperate with a human for a chance to acquire more power, participating in Dr. Adams Cyborg Daemon project when it suits him, and then disposing the scientist.

Pazuzu is a demon working under Lilith in preparation for Atun's arrival, serving as her muscle. Pazuzu is similar to many other demons as a cruel Social Darwinist that sees humans as weak. As such he only follows the strong, working for Lilith if only for a chance to serve the exceptionally powerful Atun and a chance to fight Amon. Pazuzu had respected Amon's prowess until he was overcome by a human criticizing the human during their fight.

Jinmen is an antagonist in the Devilman prologue part of Cyborg 009 vs. Devilman OVA's. Jinmen is a cruel and highly sadistic demon in great comparison to a lot of other demons displayed in the series. It would even be fair to call him outright evil. He torments his victims by keeping them alive on his shell; their screams, cursing, and pleas giving him great pleasure. This also extends to finding new targets, using ties some of his victims had with another person against them to torment and distract them so that he can savagely beat them or use their faces as shields while playing with a person's morality. However when this doesn't work, he is shown to be rather cowardly, warning his opponent about the lives on his shell as an excuse to keep him alive; which is more than likely a bluff.

Satan (or Ryo Asuka in the timeframe of the OVAs) is a supporting character in the OVA crossover film Cyborg 009 vs. Devilman. Ryo was portrayed by Satoshi Hino. Ryo is easily seen as the right hand of Akira Fudo, seeing each other as their best friends. As such Ryo assists Akira against the demons that invade the human world. This also extends to any enemy who stands against them including the cyborgs when they were thought to be a threat, shooting as 009 without mercy. Later he changes targets to Black Ghost's High Teen Cyborgs when they were directly involved in their affairs.

Akira Fudo is the titular character of the Devilman franchise and one of the main characters of the Cyborg 009 vs. Devilman OVA movie. Prior to his transformation, Miki described him as kind but weak of will, particularly with the loss of his parents. Official material states after his first transformation Akira gained a hard, dry, yet cool personality. He normally acts rather sarcastically and uninterested in most things unless his loved ones are involved, acting protective with Miki and Ryo. As Devilman, Akira is vicious towards any demons and perceived threats.

Lilith is a demoness from the Cyborg 009 vs. Devilman OVA series. She serves under the demon Atun in their alliance with Dr. Adams. Lilith is cold and calculating, utilizing sneak attacks and her converted servants to do her bidding. Like many demons, she is a Social Darwinist, believing herself and anyone stronger than her such as Atun to be superior, especially to humans. Seeing the cyborgs gives her the sight of how humanity became stronger and how these similar motives can ultimately lead to their destruction. In battle, she likes to tease her enemies, especially if they are men she thinks are worth her attention.

Sachiko was a young girl and friend of Akira Fudo, who fell to the turtle Jinmen. Sachiko was a minor character in the anime 'Cyborg 009 vs. Devilman'. Sachiko was a sweet and good natured girl. Akira cared greatly for her, making her spiteful fate all the more fated to handle.

Miki Makimura is Akira Fudo's childhood friend and love interest, serving as a supporting character in Cyborg 009 vs. Devilman. Miki is a kind girl with a strong sense of righteousness, showing bravery in the face of danger as shown when she used her school bag to throw two thugs off their moped without hesitation. She is easy to like, as shown when she makes fast friends with Eva Maria Pallares. She has romantic feelings for her childhood friend Akira Fudo, but will not hesitate to chastise him when necessary.

Dr. Adams Teufel, referred to as both Dr. Adams and Dr. Teufel for short, is a Black Ghost scientist and the creator of the High-Teen Number 00 cyborgs. He is an antagonist in the Cyborg 009 vs. Devilman OVA crossover. He is portrayed by Kamen Rider narrator Fumihiko Tachiki. Dr. Adams is a highly ambitious scientist with no fear of risks. But it were these same ambitions that caused Dr. Adams to be pushed away from his colleagues in Black Ghost as his ideas had a lot of risks and would have cost profits, particularly his extremism about mutation and his eventual concept of a "Cyborg Daemon". Like many Black Ghost scientists he has little regard for human life, seeing his projects merely as either expendable tests subjects or things he can take pride in. However, he had a soft spot for his son Edward, giving him the first cybernetic procedures to save his life.

Dr. Isaac Gilmore is one of the main characters of Shotaro Ishinomori's Cyborg 009 franchise and a supporting character of the OVA crossover film Cyborg 009 vs. Devilman. Dr. Gilmore is a wise and kind man, but at times is a bit quick-tempered. He is the 00 Cyborgs closest ally and their mentor, acting as a sort of father figure to this surrogate superhero family. They often consult him on matters involving Black Ghost, scientific anomalies caused by their weapons, or on general knowledge to investigate bizarre events (geography, science, ways of contacting Gilmore's friends in the scientific community etc.).

Apollo is a villain from Shotaro Ishinomori's Cyborg 009 franchise and plays a minor role in the prologue to the first episode of Cyborg 009 vs. Devilman. He is the leader of the Mythos Cyborgs. Like most of his incarnations, Apollo is arrogant, prideful and at times impulsive. He is also very confident in his power and is amused and frustrated by 009, often getting into competitive fights with him to prove he is the superior being and a true god.

Seth also known as Cyborg 0018 is the final member of the High-Teen Number Cyborgs created by Dr. Adams. He is the younger fraternal twin brother of Eva Maria Pallares as well as the host of the demon Atun. He (as well as his and Atun's fusion Azazel) serves as the final obstacle in the OVA Cyborg 009 vs. Devilman. Before his conversion, Seth was gentle and soft-spoken who was fond of his older sister Eva, often having to rely on her. After the merger with Atun, the newly fused Seth/Atun hybrid was homicidal, willing to kill anyone in his path. He also became turned against his sister, becoming murderous towards her, with no qualms in injuring anyone in whatever way he could to gain the upper-hand.

Abel also known as 0017 is one of the High-Teen Numbers cyborgs developed by Dr. Adams. He is often paired with John Cain Smith (0016). 0017 appears to be more curious and playful than his group-mates, likely due to his age. But in battle he is just as devious and driven as the others. He seems to like themes, particularly when facing against enemies his powers would have either an advantage or disadvantage against certain enemies, such as when Abel fought against 008 and tried to freeze him in water while playing around with 006. He is also reckless, shown when he charged headfirst into his former teammate 0018 when he became possessed by Atun with 0017 being destroyed. Among his group, Abel seemed to have been close with Cain, often being seen on Cain's shoulder and when Cain tried to avenge his destruction.