She is known as "The Last Witch of The 20th Century". The Witch Queen was said to reside in Germany along with a young Ban Midou before he was sent back to Japan to live with Maria after the incidents involving Aris Miroku.
Some time ago she sealed the doors to Babylon City to stop people who wanted to achieve the higher power of those residing there, by the cost of her own life.
Not much other than this is known about The Witch Queen.
The Evil Eye: The Witch Queen can utilize Jagan, a power which allows her to make anyone she makes eye contact with watch a one minute long illusion, though it can only be used a maximum of three times per day. As mentioned above, she can use it to change the destiny of someone. She can use it to get back someone's memory, replace someone's memories, look into their past or present, finding out everything she wants know about them, turn their brain into a vegetative state, or make them believe that they died. She can also use her Jagan to turn people into stone (although when Ban utilized this, it was done with the help of a card -- theoretically, she should need no enhancement). If she makes you believe that you've been turned into stone in the Jagan, in reality it will be as if you really turned into stone. The Jagan was also used to walk through dimensions within space and time. The Jagan is an electromagnetic wave that sends the brain waves any message that the Witch Queen desires, as if she sends in commands to the brain telling the brain that the person is dead, then the person within the Jagan will believe that she/he is dead and die. Whatever you believe is real within the illusion materializes in reality depending on if she allows it to happen of not.
Asclepius: The Witch Queen gains power from the cosmos. The God Asclepius grants her power and she concentrates it mainly into her arm. Because she relies on her constellation and the power of the cosmos she doesn't have to rely on her natural senses, strength, agility, stamina, endurance, or speed but her connection with the cosmos in order to fight.
Witch-craft: She has the ability to pull the heart out of a person's body effortlessly. She is able to use various spells such as flamethrowers, magical ki-blasts (or light beams), and magical shields. The Witch Queen is the creator of all things that are magic within the existence of GetBackers (due to her title from her original world, and her being the other creator of the World Program Building-System within the Brain Trust), so it's safe to assume that she knows every single Magic Spell.
Turning Spell: This is a spell which allows the user's speed, and power to match his/her opponents. However, any physical attacks used upon the user will only affect the person using the attack.
The Black Magic Resurrection Ceremony: This spell mostly relies on fooling the viewer by having a victim be merely in a state of temporary death. However, the curses and spells being cast around the viewer can kill anyone who hasn't received the training of a high witch.
< Chant: Blessed is the man that walketh not in the counsel of the ungodly, nor standeth in the way of sinners, nor sitteth in the eat of the scornful. But his delight is in the low of the lord; and in his law doth he meditate day and night.And he shall be like a tree planted by the rivers of water, that bringeth forth his fruit in his season; his leaf also shall not wither; and whatsoever he doeth shall prosper. Ask of me, and I shall give thee the heathen for thine inheritance, and the uttermost parts of the earth for thy possession. Thou shalt break them with a rod of iron; thou shalt dash them in pieces like a potter's vessel. Be Wise no therefore, O Ye Kings: De instructed, ye judges of the earth. Serve the lord with fear, and rejoice with trembling.Kiss the son, lest he be angry, and ye perish from the way, when his wrath is kindled but a little. Blessed re all they that put their trust in him.>
Divine Design Cards: The Witch Queen possesses one of the original decks of the Divine Design. Originally introduced as a card game, it is a deck of cards that have the power to affect reality. They have the power to cause distortion within the world and when that rift reaches a certain limit, history and time itself can be altered. This will bring about catastrophic changes to reality itself.
Sealing Spells: It was stated that the Witch Queen was the one who sealed the gates of GetBackers universe from being interfered with outside forces. She was also the one who sealed away the Voodoo King, locking him within a shell. The Voodoo King carries 3 Stigmatas, so it's safe to assume that she is one of the strongest characters introduced within the series.
Through the series of GetBackers, it is constantly told by many of the tales of the Witch Queen and her power. Many characters has stated that she was strongest witch and that her power and experience dwarfs that of any character in the series.
Ban Mido, Lucifer, Maria Noches, Der Kaiser, Masaki Kurusu, Kyoji Kagami, Makube, The Voodoo King, and even The Archive has mentioned the Witch Queen and her power at point or another. A lot of them are envious because of her power, and others are angered because of her power and her actions against them. Nonetheless, her name is something that is truly respected and feared throughout the series.