Tanya von Degurechaff

Tanya von Degurechaff (ターニャ・フォン・デグレチャフ, Tanya von Degurechafu) is one of the main characters of Isekai Quartet, and protagonist of Youjo Senki. Originally, a salaryman who was murdered 2013 and then reincarnated as a young girl into a world of magical warfare based on World War I by the god from her world, Being X. She is ranked Second Lieutenant of the Empire, bestowed the title of Von, and Wing commander of the Imperial 203rd Aerial Mage Battalion. In the Isekai Quartet World, she is a student of Class 2 and a member of the Disciplinary Committee.

Appearance
A girl with a rather petite build with blonde hair and blue eyes. She is described as having a doll-like appearance which masks her more sharp, if not more sinister, impressions. She wears her military uniform originally from her own world and her magical tool, Elenium Type 95 at the base of her neck.

Personality
An 'evil' little girl to the eyes of some. Tanya has a diligent personality and refuses any form of laziness. Due to her previous world's experience and antagonist relationship with Being X, the one who transferred her to her previous world, she has a paranoia and hatred towards Gods, and is very strict to her group of soldiers. Of course while staying the same in the new world, she has been seen to be more lax and enjoys talking to others. Despite this, she also still remains rather diligent and suspicious of her new surroundings, preferring to avoid any unnecessary attention to her or her battalion.

An example is she apologizes to those she's wrong such as Aqua, admitting her own faults. Acknowledging her temper when it comes to Gods. She also doesn't mind helping her classmates when they get in trouble with detention. Also she doesn't mind helping people improve in classes and states she can help them study if they wish to.

Plot
While testing out a new invention, Tanya hits the mysterious button that sends her to Isekai Quartet.

She confronts Ainz, thinking he is Being X and they learn that they are Isekai characters.

Powers & Abilities
Thanks to her reincarnation and the power of Being X, Tanya has immense magical power and is a strong soldier in her original Isekai world. Ainz himself states her magical aura is above 8th-tier level magic in YGGDRASIL.

Leadership: Her battalion aerial mage group can attest Tanya as a capable leader who leads them to victory.

Magical Aura: She releases this upon great rage and knocks out, frightens, and shocks those around her. Power-wise, it is considered 8th Tier level magic in YGGDRASIL by Ainz. This demonstrates how she is very powerful if not also very intimidating.

Jewel Protective Core: Tanya is capable of actually protecting her and the other Isekai boys with a strong magical barrier against the Mobile Fortress Destroyer itself. Though Tanya admits it wouldn't have held for long against such a thing.

Flight: With the air equipment and magical abilities from her world, she can fly numerous meters in the air and is highly capable at high-speed maneuvering.

Authoritative Command: Whether it's a spell or just her own will, she can command those around her. She demonstrates this on Kazuma.

Magic Resistance: She was capable of resisting Demiurge's own command spell. Not even Ainz's Despair aura affected her much. She is even immune to Ainz's Time Stop Spell.

Elenium Type 95: A powerful magic tool originally from her world that increases her overall capabilities whenever she chants her prayer.

Imperial 203rd Aerial Mage Battalion
Members of her battalion who were transferred along with her to the Isekai Quartet World. Despite the peaceful atmosphere of the school-life world, she overall remains as cold and strict towards them from their original world. In return, they still respect, if not fear, Tanya as their leader and will follow her orders accordingly. Due to her paranoia approach, she desires her battalion not try to do anything that would grab any unneeded attention. She notably is shown to interact with Viktoriya Ivanovna Serebryakov the most and share a somewhat more friendlier relationship with her.

Ainz Ooal Gown
When she first met Ainz Ooal Gown, she was immediately suspicious of his overall appearance. Because she was able to sense his great power, she even suspected him as her archenemy, Being X. When she asked to have a private conversation with Ainz and made her accusation of his identity, the two soon learn of their respective identities as humans originally from Japan. This made the two get along not only as fellow former humans from Japan, but how they were both also originally salaryman in their original human lives. Tanya now shares an overall friendly relationship with him and even casually addresses him as Ainz. She also believes him to be above cheating much to Ainz shame.

Demiurge
The two became acquainted as fellow members of the Disciplinary Committee. The two have shown to get along when it comes upholding law, order, and adding rules. Tanya also respects Demiurge for being a comrade of Ainz Ooal Gown. This has them both cooperate in stopping their fellow Disciplinary Committee member Satou Kazuma from doing any ill behavior actions.

Natsuki Subaru
Tanya has not made much interaction with Natsuki Subaru, but she overall appears to not think much of him aside from a fellow classmate. Through Aqua, she discovers how Subaru is also human originally from Japan. During the Sports Festival, the two managed to get along and work together.

Puck
She and Puck teamed up to "train" Kazuma for the sports festival.

Julius
After meeting him, Tanya admits to sharing Subaru's dislike of him.

Reinhard
She considers Reinhard infuriating due to how overpowered he is.

Satou Kazuma
The two became acquainted as fellow members of the Disciplinary Committee. She finds Kazuma's laid back and easy personality unpleasant and acts both strict and cold towards him similar to how she treats her battalion. She even does the same torturous snow training she did with her battalion to Kazuma to whip him into shape. During the Sports Festival, she comes to respect Kazuma's skills that she even stated how she would like to enlist him into the army in her world. She aided in Megumin's plan to get him out of detention along with the others.

Aqua
Tanya originally hadn't much interaction with Aqua until the School Trip during the Test of Courage. When Aqua identity her as human originally from Earth, it surprised her. When Aqua revealed herself as a Goddess who transfer Kazuma from Earth to her world, Tanya immediately began to accuse Aqua as her enemy Being X due to their similar actions and claims. This made her enrage at Aqua until Natsuki Subaru came to her defense and Ainz pointed their differences such her presence and overall personality. She apologized for her actions towards Aqua but when Aqua pointed out she's been saying she was a Goddess the entire time, Tanya realized how the information didn't really sink much into her due to Aqua's unfitted qualities as a Goddess. She currently doesn't believe Aqua is a goddess, stating she finds Aqua's claim as delusional and upsetting. Though despite that she does seem to have some care wishing to help Aqua study for tests and was upset seeing her cheating and scolding her.

Trivia

 * Tanya is the first to befriend another character (Ainz Ooal Gown) originally not from her world.
 * Tanya is the youngest of the protagonists and the entire Class 2.