Lan Asuka resembles a attractive young woman with long blonde hair, blue eyes, and a tall and glamorous figure. Her appearance even had Kazumi Takiura think she was a model. She usually dresses in a red tube top, jeans, boots, and a jacket. Later it is revealed that Asuka has a unique condition called the Lan Factor that makes her an intersex that gives her both male and female features such as breasts and a penis. To hide her male parts, Asuka takes medication.
In their transformation into the God Child, they resembles a gigantic angel with no clothing with their hair becoming a pair of large wings. Going further into their transformation, their face becomes distorted with the end of their limbs becoming bird-like talons making Asuka resemble a harpy.
Asuka on the surface is portrayed as being cynical, arrogant, yet calm. She often appears uncaring about what happens around her including to her subordinates. However, she is aware of weakness and is often able to find the weaknesses in others as well as herself. Her tone and attitude rarely ever change including in events that most people would either be gleeful or horrified. Although she follows orders and instructions, Asuka in no way cares about the position even talking down about the President of the United States behind his back. Asuka has a particular distaste for Japan, calling it the "country of [her] most disliked man" possibly referring to her father.
Asuka treats Jun like a pet even punishing her as Lady with a muzzle and threatening her in order to try and quell her behavior. During these times Asuka displays a sadistic behavior. Still, Asuka does treat Jun with some respect overtime. She also has high expectations of Jun as Asuka seemed distraught at the results that would have killed Jun. Asuka in regards to some of Jun's relationships refers to Kazumi as Jun's pet. Asuka indulges in some pleasures of her own as shown when she raped Bates out of lust as he was going under a procedure.
At the end of everything though, Asuka reveals their true character. Asuka had hated their parents for giving them a body that was subject to more changes than the average person having first been raised as boy and then having to live as a woman as they got older. They also began to hate humanity and the world as a whole for all of their flaws and sees the Devil Beast Syndrome as the pinnacle of their true wicked nature. Jun however was an exception for like Asuka, she had cursed her own fate and existence even before becoming Lady. With Lady being the representation of strife within Jun yet being so powerful, Asuka lusted for Jun ever since.
To bring her plans into fruition, Asuka manipulated many events throughout the series to bring conflict between the more peaceful Devilmen and humans causing the Devilmen to be put into concentration camps, wiping out a majority of the inhabitants. At the end, even her bond with Jun was but a means to an end as everything had been an experiment set up in Japan to measure the Devil Beast rate in order for Asuka to achieve godhood through a different form of self-induced evolution. Asuka went on to state that Jun was born solely for them and would die for them; paralyzing, raping, and tossing her into the abyss of Inferno once she was done with her.
As the God Child, Asuka shows their dominating ego to their fullest seeing themselves as the highest and most powerful lifeform of them all controlling the entire human population all while keeping the Devilmen in a comfortable prison and denying them any further rights. When Jun returned as an empowered Giant Lady, Asuka mocked her as an ugly being that did not belong in their perfect world and proceeded to try and destroy her.
As head of the H.A. Japan Branch, Asuka has full authority over its institutes, dealings, and resources including its personnel. Before her transformation, Asuka has shown herself to be a keen manipulator, using the strengths and weaknesses of others to her advantage to control events to her advantage. She also keeps and is rather skillful with handguns that she keeps on her.
Asuka is the holder of the unique Lan Factor, a genetic condition that made Asuka an intersex and later gave her control over her anatomy. Because of it, Asuka possesses a resistance to psychic abilities even from users as powerful as Satoru. Asuka is also able to cast illusions powerful enough to seem real, as shown when she made an area look like the fabled paradise as well as paralyze a Devilman by messing with their senses. Upon receiving the proper stimulus and data, Asuka is able to control her metamorphosis into the highly powerful God Child. This angelic form possesses great power able to levitate in air in a gigantic state for an unlimited amount of time and telepathically control every human on the planet, stripping them of their free will. However, they are unable to control Devilmen due to having a psychic resistance so they keep incarcerated. When entering battle Asuka utilizes beams of light that are powerful enough to inflict serious injuries in one blow, be thrown with enough force to cause a mushroom cloud, or be used in machine gun fashion that severed the arms of a Giant Lady.
Asuka was born to a Japanese mother and a Caucasian American father. They were initially raised to be a boy until years of development later had Asuka become more like a woman. Asuka had cursed her parents for giving them a body that was neither one or the other. For the remaining years of her life, Asuka had to use medication to keep her male parts from showing while working her way up in the government collaboration organization the Human Alliance, eventually becoming the head of the Japan Branch.
Asuka was the one who set loose the Devil Beasts on Jun to cause her transformation into Lady. With Jun awakened as Lady, Asuka had her put under the H.A.'s custody with Asuka becoming her overseer and sending Jun on missions to terminate selected Devil Beasts all the while having Jun's life at her fingertips. For most of the series, Asuka was shown to be indifferent to Jun as well as her ideas for peace among the Devil Beasts. As a matter of fact, Asuka had actually been sabotaging any and all negotiations between these parties as she had no desire to have the Devil Beasts out in the open. Overtime, Asuka had gotten softer and treated Jun better. But by the time Jun had gained a better understanding of everything that had happened, Jun left to confront Asuka.
Asuka creating an illusionary space reveals to Jun her true colors, revealing the effects of the Lan Factor that made her an intersex, and her feelings about how she sees the world with hate and the lust she felt towards Jun. Paralyzing Lady with her powers, Asuka proceeds to rape Jun before tossing her into the abyss that leads to Inferno. With Jun out of the way, Asuka transforms into the God Child using her psychic powers to control every human on the planet, severing their free will and by effect stopping all conflicts all the while keeping the Devilmen in concentration camps where they are cared for but not permitted to leave.
Jun however returned as an empowered Giga Lady fueled by the hate and anguish of the fallen Devil Beasts. Asuka, seeing Jun as an abomination in her perfect world readies her powers to destroy her. Lady provides much more of a challenge however, forcing Asuka to assume a more monstrous form and becoming more vicious. The raging God Child severely wounds Lady, blowing off of her arms. However, in their moment of cockiness Asuka is severed in half by Lady's Devil Cutter exploding into a shower of light. With Asuka dead, the humans regained their free will and it seems that the Devilmen have integrated into society alongside them.
- Asuka is 23 years old, 175 cm in height, and is a B blood type.
- Asuka's given name is written different ways including being written as Run, Ran, or Lan depending on the media.
- Asuka's name and appearance is based on Ryo Asuka from the original Devilman manga including their parentage, the only difference is their more drastically different personalities.
- Asuka as the God Child resembles Satan while their harpy-like state resembles Sirene.