Only watching the anime, Kaya "Orion" Saito follows the story of Attack on Titan. This oc also contains a mix of Manga, Anime(including OVA) and A.O.T Wings of Freedom information. To not be confused, AOT Manga and AOT Anime have different words compared to each other but they tell the exact same thing. In the Manga, the ones used to eliminate the Titan used by the the three branches of the Military are called Vertical Maneuvering Equipment. In the Anime, the three branches of the Military use the Omni-Directional Mobility Gear or ODM Gear for short. The difference? Nothing as the dub of the Anime simply changed it for convivence. 

"Shinzou wo Sasageyo" / "Dedicate your Hearts!"

~Orion stating the quote from Commander Erwin to Squad Orion~

English Name: Kaya "Orion" Saito
Japanese Name: カヤ「オリオン」斉藤
Nickname: "Orion"
Preferred Name: Orion, Kaya
Preferred Name with Rank: Squad Leader Saito

Current Rank: Squad Leader, Logistician 

Looks:

(https://pin.it/64d7cbQ)

Clothing(s):
(1st Suit; Survey Corp/Scout Regiment Uniform)

(2nd Suit; Reserve Survey Corp/Scout Regiment Uniform)

(https://pin.it/5caZTRO)

(3rd Suit; Personal Off Mission Uniform)

Family:
Iwakiri Saito (Father, Alive: Worker in a Blast Furnace)
Akiyama M. Saito (Mother, Alive: Sergeant of the Military Police Brigade[Manga] / Regiment[Anime])
Arata Saito (Younger Brother, Alive: Member of the 107th Cadet[Anime] / Training[Manga] Corps)

Friend(s): Squad Orion(Deep Friendship Level), 104th Cadet Corps Members, Special Operation Squad, in General to some degree everyone treating even foe as a friend, 
DOB(Date of Birth): September 6
Age(Depending on Rp, May Change): 23 - 28 

Birthplace (Which Wall, What town, etc): Wall Sina
Current Residence (Which Wall, What town, etc.): Wall Sina, Yarckel District

Species: Human 
Nationality: Japanese-American
Gender: Female, Bisexual

Height: 5' 1" (155 centimeters)
Weight: 220.0 pounds (100.0 kilograms)
Blood Type: O+

"Scout Regiment...? Are you really sure?"
"Yes ma, pa. We're not going anywhere aren't we? And every day passes more Titans come. So, why not make a difference?"
"Kaya..."
"Don't worry pa. I'll make sure to return safely"

~Kaya and her parents exchanging words, the night before going to the Cadet/Training Corps~

Field Weapon(s) & Equipment: 
Omni-Directional Mobility Gear (Anime) / Vertical Maneuvering Equipment (Manga)

(artstation.com/artwork/Kr5JER)

Transportation: Squad Orion Specially Bred Horse 
Horses are animals used for navigation and travel across vast terrain, usually in Titan-infested territory outside the Walls. They are mostly used on expeditions, though they are also used for leading carriages and getting around inside the walls. Like all other animals, their presence is completely ignored by Titans. Like most horses they have their notable traits. Top Speed of 75 - 80km/h, Endurance constant speed of 35 km/h and quite docile and don't normally frighten in the presence of Titans. 

In this case, Squad Orion Horses have two extra Gas Cylinders on each side and one Box of Snap Blades to accommodate the Squad so that their ODM/Vertical Maneuvering Gear won't run out of gas and blades that easily. Thanks to the brilliant minds of Logisticians, they were able to equip their horses with these. 

Like(s): Slaying Titans, Scouts, Wall Sina being Safe, Exploring the Unknown, Munching Food in General, Impossible-Possible Odds, 
Dislike(s): Impossible-Possible Odds(Though Orion likes the impossible odds, those that can't be deemed possible she disliked a lot), Slacking, Disrespecting the Scout's Insignia, 

Previous Rank: Cadet, Soldier, Team Leader

Rank Structure For Reference
To be used(From my understanding in the Anime):
Commander-in-Chief (Ex: Darius Zackly)
Commander (Ex: Erwin Smith)
Section Commander (Ex: Hange Zoe)
Squad Leader (Ex: Levi)
> Senior Team Leader
> Team Leader

Commanding Officer (Ex: Jean Kirstein)
Officer (Ex: Mikasa, Connie,)
Soldier/Cadet (Ex: 104th Training Corps Members)

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More Information on Ranking Structure: 
(https://attack-on-titan-regiments.fandom.com/wiki/Military)
>High Command [HC]
Premier
Deputy Commander
Commander (Ex: Erwin Smith)

>High Ranks [HR]
Captain/Squad Captain (Ex: Levi)
Section Commander (Ex: Miche Zacharius)
Lieutenant

>Middle Ranks [MR]
Warrant Officer
Master Sergeant II
Master Sergeant I
Sergeant Major
Staff Sergeant
Sergeant

>Low Ranks [LR]
Corporal
Lance Corporal
Private First Class
Private
Recruit(Cadets; Ex: 104th Training Corps Members)

Ranking Structure Under Erwin Smith: 
Under Erwin Smith the 13th Commander, there were 4 Squad Leaders, 1 Senior Team Leader, 8 Team Leaders, 6 Medics, 5 Equine Veterinarians, 5 Payroll Staff Soldiers(also Team Leaders) and 270 Soldiers. The Survey Corps/Scout Regiment was divided into 10 teams, each led by their respective Team Leaders who answered to their Squad Leaders, who in turn answered to the Commander. 

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"私たちは人類の希望です。私たちが倒すすべてのタイタンは、その希望に一歩近づきます。/ We are the Hope of Mankind. Every Titan we slay is one step closer to that Hope."

~Kaya reminding her squad what Scouts are~

Affiliation:
Survey Corp (Manga)
Scout Regiment (Anime)

Corps/Regiment:
Survey Corp (Manga)
Scout Regiment (Anime)

Backstory: (The backstory of Kaya Saito contains spoilers of Season 1 through the Final Season. Read on your own risk. This is also a Work in Progress with the Backstory not finished just yet)

Prelude
Born in Wall Sina, she was taught about their lives and history with the Titans suddenly appearing and eradicating almost all of the Human Race that they were forced to take shelter behind the safety of the 3 walls. As they reached the Industrial Age, she had grown quite well over the years and thanks to her prestigious parents were able to get her into Higher Education and since her mother, a member of the Military Police Regiment, she had received prior training before attending the Corps. Hand-to-Hand and Limited Firearms training. This is where her mother told her the different branches of the military. Three specific branches: Scout Regiment, Garrison Regiment, and Military Police Regiment. She explained the three regiments and  their purpose in life. 

Upon learning this, the day before she went to train with the Cadet/Training Corps, Kaya told her parents that she would join the Scout Regiment in hopes to end Humanity's isolation and fight back against the Titans. Both of her parents know the history and high Casualty Rate of the Scout Regiment and tried to persuade her to join a different one. But, Kaya's determination proved them otherwise also promising them that she would return back home safe in one piece and/or write a letter to reassure them about it. After some more convincing, they let up and supported her wish. 

Whilst training in the Cadet/Training Corps, her mother gave birth to a younger sibling, a brother to be exact. Upon learning this, she was determined to ace all training given to her not only for her family and younger brother, but for the next generation of Humanity. Acing her training, she graduated Top 1 of 10 in her class. Although most joined the Military Police, she joined the minority of the Scout Regiment. 

On her 1st expedition outside the wall, putting all of the training and skills up to the test, she was determined to get a Titan elimination for the first time. Kaya's smile seeing the outside beyond the Walls turned upside down before seeing fellow Scout members getting eaten and grabbed from their horses by normal Titans. The horror sets in, spaced out as she rode her horse. Kaya was also about to get grabbed by a Titan but a Scout Member snapped her out of trance, barely avoiding the Titan. Realizing one close, Kaya used her ODM/Vertical Maneuvering Gear to slingshot herself to the nape of the Titan slashing it confirming her 1st elimination. The expedition, like many others yield little to no success. Returning from her 1st expedition, everything settled into her the horrors outside the Wall and the true brutality of the Scout Regiment. However, despite all of this, Kaya had managed to push on at the cost of her mental health that would sometimes take a toll on her. 

Continuing to do expeditions and sometimes missions around the wall, she had gained a lot of experience from eliminating Titans and her expert handling of the ODM/Vertical Maneuvering Gear. So much so, she was given the position of Team Leader leading her own team of Scouts. As time went on, when doing expeditions and missions, Kaya also lost some comrades along the way mostly by her Team costing even more of her Mental Health. When a Commander's shift, then came Erwin Smith, the 13th Commander of the Scout Regiment/Survey Corps. Upon learning about her problems, Erwin would constantly talk to Kaya about her problems. This helped her alleviate some of the Inner Pain she is dealing with and as a result, becoming a habit to eat anything she has on herself as a way to cope. At the time, under Erwin Smith, she had became an Elite member of the Corp/Regiment also becoming a Squad Leader having her own Squad named Squad Orion or for others, the Tactical Support Squad or TSS (Squad History down below).

Leading up to the 1st season of AOT, Squad Orion racked up a 110 confirmed eliminations and is regarded as the 2nd Best to Captain Levi's Special Operation Squad. When they are busy, the Tactical Support Squad is their 2nd choice to call for reinforcements. 

Prelude Leading up to Season 1, 49th Expedition Beyond the Walls, Before the Attack on Trost District
The primary objective Scout Regiment's expedition outside the walls was to make a move to recover Wall Maria, which had fallen 5 years earlier. Their job was to to establish a supply base in the abandoned areas and open a path so that a much more larger force could be sent to Shiganshina District, where the wall had been broken. The Scout Regiment represented the peak of human wisdom. Arriving at the Shiganshina District, with Levi Squad and the rest of the Scouts taking on Titans, Kaya and the TSS stayed close with the Supply Teams just in case any Abnormal Titans show up. Kaya engaged 3 to 15 meter Titans that went near the Supply Teams till it was clear to set up thanks to combined efforts of Levi, Kaya and the Scouts, 

With the Core Forces arriving, all squads set up on the edge of town whilst Squad Levi and Commander Erwin took out titans at the center. Squad Orion stayed in the edges of Town to take out Titans entering. Once the Titans in the center were eliminated, Section Commander Zoe reported Titans entering the South. Squad Levi and Squad Orion took out the Group of Titans even a large Abnormal Titan. Once the threat was subjugated, now Erwin wants to secure a path to the Shiganshina District. With Squad Levi deployed, Kaya's Squad Orion stayed at the base to help the Logisticians and other scouts unload whilst also heading as the base's main primary security unit against any Titans. It was also noted that fighting in plains hinders the full potential of the ODM/Vertical Maneuvering Gear. It was also at this time the discovery of Ilse Lagnar's Notebook, a Scout from the 34th Expedition, 2nd Battalion in charge of the Perimeter Defense. With approval from Commander Smith, and support from the Special Operation Squad led by Levi, succeeded in organizing the 1st ever expedition beyond Wall Maria to capture a Titan. New methods from Hange resulted into a success, with NO Human Life Lost. 

However, during transport, multiple 15 meter Titans were seen. Commander Smith's plan was to link Squad Orion and a couple of Scout Teams to Squad Levi and Hange meeting in the middle. Subjugating the 15 meter Titans, they succeeded. During this short time of peace, Kaya visited the Old Town trying to reimagine life before the fall. 

Prelude Leading up to Season 1 Episode 9, 49th Expedition Beyond the Walls, Before the Attack on Trost District
In another part of the Shiganshina District, Core Forces were almost massacred. Squad Levi and Squad Orion arrived to help specifically Orion helping the remaining Core Forces against the Titans, and Petra tending to the wounded soldiers below. To the combined efforts of both Squads and Scouts they were able to eradicate the Titans and relieve the Core Forces. However, Erwin brought the bad news of the Titans heading North towards the town, that the walls might be Compromised. With all units now retreating back to Trost District, Levi was tasked to to be the Rear Guard and stop any Titans chasing them. Kaya was tasked the flanks. With that, they made the hasty retreat back to the Trost District whilst slaying Titans. Kaya managed to save 3 trapped Scout Teams that were cut off the Battle Formation thanks to the Distress Smoke Signals. The remaining Scouts were integrated to her Squad for the time being. Commanding Squad Orion and 9 more Scouts, Kaya led the large group back to the wall and was towards the large hole made by the Colossal Titan however, it was blocked by a Huge Boulder. 

Season 1, Episode 13, Arrival of the Scout Regiment/Survey Corp,

This is at the time when Levi arrived to save Eren, Mikasa and Armin from the two Titans. With efforts combined from the Scout Regiment/Survey Corp and the Garrison Regiment's Corps of Engineers, Wall Rose was successfully defended against the Titans. During this time, Kaya met Annie Leonheart and the two hit off with each other developing some feelings. As time progressed, the two were seemingly together aside when Berthold and Reiner needed Annie for something. Kaya thought none of it as she remained oblivious to the male duo. 

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Personality: Defender, Observant, Feeling, Intuitive, Calculated Thinking, Smart, Disciplined, Honest, Professional, Creative, Optimistic, 

Strengths:
Highly Motivated, Charismatic, Pressure, Adaptable, Air Superiority through ODM/Vertical Maneuvering Gear, Hand-to-Hand Combat, 3d Combat, Enhanced Strength, Endurance, Speed, Agility and Reflexes,  

Weaknesses:
Reliance in ODM/Vertical Maneuvering Gear(Though the use of ODM/Vertical Maneuvering Gear gives them the necessary advantage against Titans, she heavily relies on it and without it, she thinks she is worthless to the Scout Regiment/Survey Corps)
Trauma
Impatient
Passive
Takes blame of others even if she didn't do it regardless
Pressure (Also a strength, the peer pressure from others that she would do a successful mission/strike/operation sometimes gets a toll on her)

Relationship Status(Depending on Rp, May Change): Single
Crush(Depending on Rp, May Change): Annie Leonheart, Zoe Hange, 
Life-Long Dream: "Rid of the Titans on this World, whatever it takes!", "When this war ends against the Titans, I want to explore the world and see beyond the stars wherever it may take me"
Goal(s): Eliminate all Titans and preserve Humanity
Habit(Always doing): Munching on Food (Whether it is on a mission or off mission, she is always seen munching food)
Fear(s): End of Humanity, The future of her Parents and Sibling if she didn't return home

Health
Memory (any issues with this?): None
Sight (do you need glasses?): 20/20 
Mental (Any problems?): Trauma, PTSD (Suppressing via Habit)
Physical (Do you take care of your body or harm it? Also include injuries): No Injuries
Sleep patterns (how you sleep and how much rest do you get?): 7 to 10 Sleep Hours per Day, 5 to 10 Hours Rest, 1 Day to 1 Week depending on Injuries
Allergies/Other: None

"We're here to help!"

"It's Squad Orion!" 

"Everyone Disperse! Mark your Targets!"

~Kaya and Squad Orion coming the rescue of an outnumbered Scout Team~

Abilities/Statistics (1- lowly skilled, 10- highly skilled)
Maneuvering Gear: 10
Intelligence: 9
Martial Arts: 9
Battle Skill: 9 
Agility: 10
Strategy: 8 
Teamwork: 10
Passion: 10
Total: 75/80

Training: Extensive, Brutal, Experienced, Disciplined, Battle-Hardened, Tough

Other(In General): Finished Grade Top 1 in her Cadet/Training Corps Years

Theme:
(Iconic Arrival)

https://youtu.be/8OkpRK2_gVs

(https://youtu.be/8OkpRK2_gVs )

(Last Breath, Last Stand)

https://youtu.be/qKK-GVTxqow

(https://youtu.be/qKK-GVTxqow)

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Squad Orion; Tactical Support Squad (TSS)

English Name: Tactical Support Squad, Squad Orion 
Japanese Name: 戦術支援部隊  , オリオン隊

Affiliation:
Survey Corp (Manga)
Scout Regiment (Anime)

Corps/Regiment:
Survey Corp (Manga)
Scout Regiment (Anime)

Transportation: Squad Orion Specially Bred Horse
Horses are animals used for navigation and travel across vast terrain, usually in Titan-infested territory outside the Walls. They are mostly used on expeditions, though they are also used for leading carriages and getting around inside the walls. In this case, Squad Orion Horses have two extra Gas Cylinders on each side and one Box of Snap Blades to accommodate the each individual members. This is to ensure that their ODM/Vertical Maneuvering Gear won't run out of gas and blades that easily. 

Squad History(Anime/Manga Mixed): Like Captain Levi's Squad(Special Operations Squad), Squad Orion(Tactical Support Squad) is a sub-unit of an elite squad of the Scout Regiment handpicked by none other by Squad Leader Kaya Saito. Highly trained, Highly skilled and Highly motivated, this squad also comprised of elite soldiers within the Scout Regiment/Survey Corps

2nd to the Special Operations Squad, TSS first began during the stages of expedition where Kaya Saito, former Team Leader was promoted to lead her own Special Unit. Kaya seeing the horrors outside of the Walls handpicked the best to be in her Squad who met up to her standards. 

This consisted of 5 more members, excluding Kaya, that are highly-trained/experienced ODM users, emphasizing sufficiency, stealth, speed, and tactical coordination with one another. Their squad was mainly to support regular Scout Teams and acts as a vessel met up to it's specifications. Their primary job? Deep Reconnaissance, Unconventional Warfare, and by the name itself, Tactical Support, to relieve and support Scout Teams who used a Distress Smoke Signal and complete Mission Objectives. 

Clothing Description: All members of the military, including the Cadet Corps Instructors, wear similar uniforms consisting of a short, light brown jacket with the badge of the Regiment on both shoulders, on the front left pocket and on the center of the back, a light-colored shirt, a dark brown sash around the waist covering the hips, white pants, and dark brown knee-high leather boots. Scout Regiment members often wear a heavy, green, hip-length hooded cloak with the Wings of Freedom on the back.