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.

She is also slightly childish, as she argued about liking salt and pepper over other foods with Ainz.

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. It increases further when she prays and bolsters offense and defense.

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.
 * Prayer: Whenever Tanya chants her prayer to Being X which works in conjunction with her Elenium Type 95, both her mental, physical, and magical abilities increase exponentially. She is able to use this to increase the effectiveness and strength of her magic such as her Protective Core which she used to protect herself from a combo attack between Ainz and Megumin.

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.

Erich von Rerugen
She has a deep respect for him and (in her eyes) gets along fine with him. Unknowing of the fear he has for her. During the Valentine's Day episode, she is the only person of the battalion to give him chocolate.

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.

Though she can argue with him. particularly when involving what to place on a meal. Not to mention started questioning his acquired 'taste' when Megumin tells her he likes her type of traits.

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 classmate. Through Aqua, she discovers how Subaru is also human originally from Japan. She also sympathizes with him due to the fact that they both have to deal with their respective curses. During the Sports Festival, the two managed to get along and work together. She felt bad for him seeing his love for Emilia isn't the same for him.

Roswaal L. Mathers
Initially, Tanya viewed Roswaal as a "clownish yodeling fool". Over time, she respected him as a teacher.

When the "Test of Courage" was coming to an end, Tanya apologized to Roswaal for her outburst.

During field day, Roswaal observed that Class 2 was losing and told the class (especially Tanya) about the cavalry game. Later in Tanya's shock; Roswaal, Mr. Rerugen, and two other teachers (whom Kazuma and Ainz recognized respectively) entered the cavalry game competing against the students. After her unsuccessful attempt to grab the headband from Roswaal, a gigantic destructive machine (whom Kazuma recognized as Mobile Fortress Destroyer) entered the scene before Roswaal used magic on her team.

During science class, Tanya was dismayed to find Roswaal doing nothing to stop Megumin from using explosion magic.

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

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 identify her as human originally from Earth, it surprised her. When Aqua revealed herself as a Goddess who transferred 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 enraged at Aqua until Natsuki Subaru came to her defence and Ainz pointed their differences such as 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.

Megumin
Tanya respects Megumin's power, but berates her for canting too long and demands she chant quicker.

Naofumi Iwatani
As a matter of first impression, Tanya found the young man to be rude for walking out without saying a word before Roswaal told the class that he could called "Shield".

After being dragged into Class 2's dodge ball game, Tanya counted on the "Shield Man" for their victory.

Trivia

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