Janus was the Marquis in the Mikene Empire and Chief Adviser to Minister Argos in the Intelligence Army, taking the position held by Archduke Gorgon following his death. She wore a long Red Robe, a necklace made of green color pearls and held a staff in hand at all time. The top of her long hair was sharpen in the form of horns, her skin was pale and was always seen been accompany by a Black Cat at all times.

Janus was capable to show Mystical Abilities, though this is thanks to the enhancements of the Empire's technology: these were Teleportation, Hypnosis, Flight and turning Invisible, in the Manga, she demonstrated to have superhuman strength, capable to tear a person vertically in half. She could fire lasers from her eyes, as well destructive beams from her staff, this powers at time would rival the Mechas own strength and helped her fend off their attacks, showing her to be a real threat in her own right in her human form. Janus used deception and tactics rather than overwhelming brute force over her enemies, and was particularly talented in the Mastery of Disguises, capable to look like any woman without calling attention to herself when she sneak into the enemy base, in one occasion, she disguise as Sayaka in the anime.

Janus is best known for two key features: One was the fact she had two faces, and her head would spin 180 degrees to show them – one face, and the one she was seen the most often, was that of a young beautiful woman, while the other was that of an old evil hag. In her Hag face, her hair would change shape, like raised spikes and her skin would change from pale to green. She also show fangs instead of teeth in this form.

The Second and most interesting featured is that she had her own Mecha, rather than been infused into the Mecha like so many of her Comrades: named Janus Koshaku in the Manga, she could leave it at any time, still, a form of connection with it remain, and the Mecha form of her is seen operating and giving orders, even though its pilot was not riding it. The Cockpit was located on the left Brest of the Robot.

The Janus Koshaku is built in her image, showing horns in its hair style, with Black and Pink colors. The face mimics Janus' Old Hag face. It have a Purple Torso and Gray Arms and Legs, it hands resemble gloves with long sharp claws instead of fingers, and wore a light purple skirt. It was adorn with a black necklace and belt with light yellow orbs. In the anime, it was shown to shape shift into a full normal size human when Janus sneak into the lab on one occasion with her pilot still inside.

In both the anime and Manga, Janus ascends as replacement of the late Archduke Gorgon after her demise, becoming the Commander and Chief of the Volcano Island Base Gorgon built and died for, containing its own Fleet of Warrior Beasts under the Intelligence Army. While she had a Contingency of Mikene Soldiers, she was often served by the Catloups Corps, Humanoid Cat Cyborgs who did Infiltration and Assassination missions, and would use Tactics that would overwhelm her enemies, though they would escape barely. Though, in the Manga, she kills Boss' cousin, Misato, in front of Tetsuya.

In the anime, Janus continues to maintain an active role, from her introduction on Ep.23 till the end of the series, and held command of the Volcano Base until its destruction, though she survived. When Argos was killed, she saved his Master's head, and held on to it during the Final Mission, losing it when Prof. Kabuto launch the Science Fortress in a Kamikaze attack on the Battleship Demonica. When the Mazingers, Venus A and Diana A joined up to use their energy attacks on the wreck, Janus was still inside it, when the Engine exploded, she gets tossed onto the main computer causing an energy feedback that Destroy Demonica, thus dying in resulting Explosion with the rest of her High Command.

In the Manga, Janus met her end after she killed Misato and ran with her minions to he Volcano Hideout. She challenge Tetsuya and his team to a battle, using her minions and Beast she fought them to a standstill, until the Volcano erupted. She and her Servants where caught in the resulting Collapse.

Her other major appearance in the Mazinger franchise was in of Volume One of the Mazinger Angels Manga, in the two part Chapter arc “The Suspicious Lady, Madam Janus”. Here she is human who operates a Night Club suspicious in the murder of various beautiful women. Jun proceeds to investigate the murders with the help of Inspector Ankokuji. The two become under siege by the Gynoid Assassins Gamia Q. After they failed, she unleashed Garada K7, but is taken down but the Mazinger Angels. When she tried to escape, her true form is reveal as that on an old Woman, she is afterwards arrested for the murders. Inspector Ankokuji later discovers she used drugs to rejuvenate herself and killed the women out of Jealousy.