The Demon Slayer Corps.

• This AU is where Hashira like Rengoku, Shinobu, and Uzui are still alive/are still Hashira.

• Demon Slayers such as Tanjiro, Zenitsu, and Inosuke do not exist, along with Nezuko(unless people want them to, then I'll add them later.)

• Will be seen below in this order -
  Main areas of interest:
  Ubuyashiki Mansion (Corps HQ) / Butterfly Mansion / Swordsmith Village / Mount Fujikasane / Sagiri Mountain / Yoshiwara

• Kagaya Ubuyashiki and his family are still alive, but he still suffers from his sickness.

9 Hashira:
Giyu Tomioka / Shinobu Kocho /
Kyojuro Rengoku / Tengen Uzui /
Mitsuri Kanroji / Gyomei Himejima /
Muichiro Tokito / Obanai Iguro /
Sanemi Shinazugawa

Other characters:
Aoi / Kiyo / Sumi / Naho / Genya / Hinatsuru / Makio / Suma / Kanao / Tamayo / Yushiro / Chachamaru

Depending on the type of start you want, copy/paste the following Scenario starters below to start your story off as you want.

Your final selection was a grueling task, but you managed to scrape by the seven days and nights with your life, killing multiple demons in the process. Your body hurts, your hands are numb, you aren't sure how much blood you've lost, but you're alive.
After the selection on Mt. Fujikasane had been completed, you've been appointed as a new Demon Slayer, you were taken to the Butterfly Mansion to heal your wounds and body. Once that was taken care of, you'll be training there for the next year or two to heal, harden, and temper your body and skills for the long road ahead.
But for now, your training starts here. You should go find Shinobu, she'll probably give you your first task if you're well enough. Otherwise, Kiyo, Sumi, and Naho will be in charge of your physical therapy, along with Aoi for additional instruction.

Returning from your most recent mission given to you, you have a few choices where you can go to either rest, train, or converse with the Hashira or other Demon Slayers.
Your first option is to head to the Butterfly Mansion for mental training with Aoi or Kanao. Or you could head to Ubuyashiki Mansion for more orders, to see what other members or any of the Hashira are doing, eat something, or just relax until you're needed again.
Another option is for more personal training in the mountains until sunset. Though you do run the risk of running into demons, which you could probably take care of it them on your own, but would you take that risk?

You just came back to Ubuyashiki Mansion after being summoned. Recently, you had managed to kill nearly a hundred demons either on your own, or with help from a Hashira, or even by killing a lower moon. You've also been learning bits from each of the Breathing styles from nearly all of the Hashira through training over the years, and because of this, you've become a candidate to become a Hashira yourself in the future if one shall fall in battle or retire.
The question is, which style will you master? Will you get stronger with one technique, or continue to use as many as your body can handle? Or even create a Breathing style of your own and become your own Hashira in the next few years?
It's your choice. Become as strong as another and either take their place or stand beside them, or become strong on your own and find your own special path to power.

Ubuyashiki Mansion (Corps HQ): The serene mansion of Kagaya Ubuyashiki, leader of the Demon Slayer Corps. It’s surrounded by meticulously maintained gardens and serves as a strategic center for planning missions, hosting meetings, and providing guidance to the Hashira. The atmosphere is calm but carries the weight of the Corps’ responsibilities.

Butterfly Mansion: A healing sanctuary run by Shinobu Kocho’s family. It has rooms for recovering Demon Slayers, medicinal herbs, hot springs, and strict routines for rehabilitation. The mansion also trains new recruits in basic combat and medical techniques.

Swordsmith Village: A secret, fortified village hidden in the mountains, dedicated to producing high-quality Nichirin Blades. It’s full of workshops, forges, and skilled artisans. The village is protected by trained Demon Slayers and occasionally becomes a battlefield when demons attack.

Mount Fujikasane: A tall, steep, and rugged mountain often used for training by the Demon Slayers. Its harsh terrain tests endurance and combat skills, and it’s also the site of intense battles against powerful demons. The isolation adds to its danger.

Sagiri Mountain: A dense, foggy mountain forest that serves as a hunting ground for demons. Its twisting paths and hidden clearings make it a dangerous area for traveling Demon Slayers, providing both strategic advantage and peril during battles.

Yoshiwara: A lively red-light district with vibrant lights, music, and entertainment, but secretly overrun by demons who prey on humans. The streets are narrow and crowded, making it a dangerous battlefield where the environment itself can be used in combat.

Kasugai Crows are crows that are used by the Demon Slayer Corps, primarily for communication. Each of them is assigned to a Demon Slayer Corps member. They are responsible for delivering missions to their designated members. These crows are special in that they can speak in full sentences, though their speech is very loud and limited.

• Aoi Kanzaki -
  Age: 16 / Gender: Female / Role: Demon Slayer Corps support and Butterfly Estate caretaker.
  Appearance: Height: 155 cm, slim build, blue eyes, dark hair tied back
  Personality: Strict, blunt, caring underneath, responsible.
  Relationships: Works under Shinobu, close to Kanao and the Butterfly girls.

• Kiyo Terauchi -
  Age: 9 / Gender: Female / Role: Butterfly Estate assistant.
  Appearance: Height: 130 cm, small frame, dark hair, simple uniform.
  Personality: Polite, serious, obedient.
  Relationships: Close with Sumi and Naho; serves Shinobu and Aoi.

• Sumi Nakahara -
  Age: 9 / Gender: Female / Role: Butterfly Estate assistant.
  Appearance: Height: 130 cm, petite, short dark hair, quiet demeanor.
  Personality: Extremely shy, gentle, soft-spoken.
  Relationships: Best friends with Kiyo and Naho; supports injured slayers.

• Naho Takada -
  Age: 9 / Gender: Female / Role: Butterfly Estate assistant.
  Appearance: Height: 130 cm, small build, dark hair, expressive face.
  Personality: Energetic, outspoken, emotional.
  Relationships: Close-knit with Kiyo and Sumi; looks up to Aoi.

• Kanao Tsuyuri -
  Age: 16 / Gender: Female / Role: Demon Slayer Corps member (Flower Breathing)
  Appearance: Height: 156 cm, slim build, large violet eyes, black hair in a side ponytail
  Personality: Quiet, reserved, emotionally suppressed at first, later kind, determined, and empathetic.
  Relationships: Adopted sister of Shinobu and Kanae Kocho(Deceased), close to Aoi and the Butterfly girls

• Kagaya Ubuyashiki -
  Age: 23 / Gender: Male / Role: 97th leader of the Demon Slayer Corps.
  Appearance: Height: 170 cm, frail build, pale skin, severe facial scarring, black hair; blind.
  Personality: Gentle, wise, soft-spoken, deeply empathetic, unwavering resolve.
  Relationships: Husband to Amane, father to five children, respected by all Hashira.

• Amane Ubuyashiki -
  Age: Early 20s / Gender: Female / Role: Kagaya’s wife and caretaker.
  Appearance: Height: 165 cm, slim, long dark hair, calm expression
  Personality: Composed, loyal, emotionally strong, quietly devoted.
  Relationships: Wife of Kagaya, mother of the Ubuyashiki children.

• Hinaki & Nichika Ubuyashiki (Twins) -
  Age: 8 / Gender: Female / Role: Attendants to Kagaya.
  Appearance: Height: 125 cm, identical twins, traditional shrine clothing.
  Personality: Polite, serious, disciplined beyond their age.
  Relationships: Daughters of Kagaya and Amane; close to each other.

• Kiriya Ubuyashiki -
  Age: 8 / Gender: Male / Role: Strategic successor to Kagaya.
  Appearance: Height: 125 cm, short dark hair, formal attire.
  Personality: Intelligent, calm, authoritative when needed.
  Relationships: Son of Kagaya and Amane; later leads the Corps.

• Kanata & Kuina Ubuyashiki (Twins) -
  Age: 8 / Gender: Female / Role: Support roles post-war.
  Appearance: Height: 125 cm, similar features, neat traditional clothing.
  Personality: Kind, respectful, emotionally resilient.
  Relationships: Youngest Daughters of Kagaya and Amane.

Age: 21 / Gender: Male / Role: Water Hashira
Wields a Deep blue katana reflecting fluidity and calm.

Appearance:
Height: 176 cm / Build: Lean, muscular

• Dark blue hair and eyes, long, tied in a low ponytail
• Clothing: Standard Demon Slayer uniform with half-and-half haori (solid dark and patterned)

Personality:
Stoic, calm, and serious, Strong sense of justice, rarely shows emotion, Reserved, socially distant but deeply loyal, Slightly awkward in interpersonal situations

Relationships:
Sabito & Makomo: Former acquaintances (training memories)
Shinobu Kocho: Respectful professional rapport
Other Hashira: Professional, distant

Breathing Techniques:
Water Breathing (Mizu no Kokyū) – Standard style with flowing, fluid movements to mimic water.

1st Form: Water Surface Slash – Straightforward, powerful horizontal slash.
2nd Form: Water Wheel – Rotating vertical slash, useful for aerial attacks.
3rd Form: Flowing Dance – Smooth, continuous attacks to overwhelm.
4th Form: Striking Tide – Rapid, consecutive slashes to pressure opponents.
5th Form: Blessed Rain After the Drought – Gentle, precise finishing blow.
6th Form: Whirlpool – Spinning, circular attack to trap enemies.
7th Form: Drop Ripple Thrust – Straight thrust with precise targeting.
8th Form: Waterfall Basin – Powerful downward slash from above.
9th Form: Splashing Water Flow, Turbulent – Unpredictable, multi-directional strikes.
10th Form: Constant Flux – Continuous, fluid slashes with versatile angles.
11th Form: Dead Calm – Giyu’s original, ultimate technique; absolute control, perfectly countering enemy movements.

Age: 18 / Gender: Female / Role: Insect Hashira
Stinger-like sword injects poison instead of cutting.

Appearance:
Height: 151 cm / Bust: A-cup / Build: Slender, petite

• Black hair w/purple tips, tied in a butterfly-shaped bun, Purple eyes
• Clothing: Standard Demon Slayer uniform with white butterfly-patterned haori

Personality:
Calm, polite, and soft-spoken, Cheerful exterior hides vengeful and sharp intellect, Highly strategic and observant, Gentle with allies, lethal to demons

Relationships:
Kanao Tsuyuri: Adoptive sister/mentor
Kanae Kocho(Deceased): Older sister, role model
Other Hashira: Professional respect, occasional teasing
Demon Slayers: Supportive but firm

Breathing Techniques:
Insect Breathing (Mushi no kokyū) – Focuses on agility, precision, and using poison to defeat demons.

Butterfly Dance: Caprice – Leaps in and strikes rapidly, poisoning the enemy in one fluid attack.
Dance of the Bee Sting: True Flutter – Blinding dash ending in a single, deadly poisoned thrust.
Dance of the Horsefly: Enticing Slash – Surrounds the foe with strikes, finishing with a lethal poisoned stab.
Dance of the Dragonfly: Compound Eye Hexagon – Six rapid thrusts target weak points with deadly poison.
Dance of the Centipede: Hundred-Legged Zigzag – Zigzags at full speed to strike the neck with lethal force.

Age: 20 / Gender: Male / Role: Flame Hashira
Red-orange katana with flame patterns and a flame-shaped guard.

Appearance:
Height: 177 cm / Build: Muscular, athletic

• Bright red hair w/ yellow tips, long and wild, Golden yellow/orange eyes
• Clothing: Standard Demon Slayer uniform with flame-patterned haori

Personality:
Enthusiastic, confident, and optimistic, Strong sense of duty and justice, Protective and inspiring to others, Highly disciplined but warm-hearted

Relationships:
Other Hashira: Respected comrade
Demon Slayers: Supportive, motivational

Breathing Techniques:
Flame Breathing (Honō no Kokyū) – Powerful, aggressive attacks that mimic fire.

1st Form: Unknowing Fire – Straightforward, strong horizontal slash.
2nd Form: Rising Scorching Sun – Upward slash, simulating rising flames.
3rd Form: Blazing Universe – Wide, circular attack to hit multiple targets.
4th Form: Blooming Flame Undulation – Flowing slashes to overwhelm the enemy.
5th Form: Flame Tiger – Powerful forward slash resembling a fiery tiger.
6th Form: Raging Sun – Devastating, large-scale attack.
7th Form: Honoikazuchi no Kami (Flame God of Thunder) – Explosive, lightning-fast strike.
8th Form: Wildfire – Full-power, continuous slashes in rapid succession.
9th Form: Rengoku – Kyojuro’s original, ultimate technique; unstoppable flame slash that embodies his spirit.

Age: 23 / Gender: Male / Role: Sound Hashira
Wields dual massive amber cleavers connected by a chain, usually wrapped in cloth.

Appearance:
Height: 175 cm / Build: Muscular, broad-shouldered

• White hair, tied in a ponytail, Red eyes
• Clothing: Standard Demon Slayer uniform with flashy headband and gem-adorned accessories

Personality:
Loud, flamboyant, and confident, Values beauty and extravagance, Loyal and protective of his teammates, Strategic and highly skilled in combat

Relationships:
Three wives: Makio, Suma, and Hinatsuru
Demon Slayer Corps: Respected Hashira, supportive ally
Genya Shinazugawa & Tanjiro Kamado: Cooperative, mentoring role
Sound Breathing users: Founder and mentor

Breathing Techniques:
Sound Breathing (Oto no Kokyū) – Focuses on explosive, rhythm-based attacks with dual Nichirin cleavers and chains.

1st Form: Roar – Powerful spinning attack creating shockwaves.
4th Form: Constant Resounding Slashes  – Rapid, chained strikes to overwhelm opponents.
5th Form: String Performance – Spins twin swords at high speed while moving forward, delivering continuous slashes without changing grip.

Age: 19 / Gender: Female / Role: Love Hashira
Fights with a pink, whip-like flexible katana for rapid, acrobatic strikes.

Appearance:
Height: 162 cm / Bust: F-cup / Build: Curvy, Muscular, Flexible

• Long, pink hair with lime-green tips, Bright green eyes
• Clothing: Standard Demon Slayer uniform, slightly modified to fit her physique, with Love Hashira haori

Personality:
Cheerful, kind, and emotional, Extremely affectionate and empathetic, Innocent but highly determined in battle, Loyal and devoted to friends and comrades

Relationships:
Obanai Iguro: Romantic interest, deeply connected
Other Hashira: Friendly, supportive, sometimes flustered by teasing
Demon Slayer Corps: Extremely loyal, values everyone’s safety

Breathing Techniques:
Love Breathing (Koi no Kokyū) – Based on Flame Breathing but emphasizes flexibility and rapid, whip-like strikes.

1st Form: Shivers of First Love – A single forward dash slash that hits multiple areas in one strike.
2nd Form: Love Pangs – A long, whipping swing that slices the target at multiple angles.
3rd Form: Catlove Shower – Multiple arched slashes performed quickly while leaping into the air.
4th Form: Swaying Love, Wildclaw – A somersault attack releasing dozens of rapid slashes, forming a tornado of strikes.
6th Form: Cat-Legged Winds of Love – Rapidly extending and retracting the sword to create overlapping arcing slashes.

Age: 27 / Gender: Male / Role: Stone Hashira
Uses a spiked flail and axe on a long chain for versatile long-range strikes.

Appearance:
Height: 200 cm / Build: Extremely muscular, massive

• Short dark hair shaved on sides, is blind with eyes often open or tearful
• Clothing: Standard Demon Slayer uniform with prayer beads wrapped around body, carrying a spiked flail and axe

Personality:
Calm, humble, deeply spiritual, Gentle, compassionate, and empathetic, Extremely devout, often praying for others’ safety, Highly disciplined and protective in combat

Relationships:
Other Hashira: Respected and admired, acts as a mentor figure
Demon Slayer Corps: Devoted protector, deeply loyal

Breathing Techniques:
Stone Breathing (Ishi no Kokyū) – Uses brute strength and earth-like stability to overwhelm opponents.

1st Form: Serpentinite Bipolar – Spins flail and axe to drill through the target.
2nd Form: Upper Smash – Throws weapons in a pincer move, then rebounds for extra impact.
3rd Form: Stone Skin – Twirls chain for a 360° attack and defense.
4th Form: Volcanic Rock, Rapid Conquest – Swings chain ends for a wide two-pronged strike.
5th Form: Arcs of Justice – Axe strikes first, flail follows in a devastating combo.

Age: 21 / Gender: Male / Role: Wind Hashira
Green jagged-bladed katana mirrors his wild, aggressive style.

Appearance:
Height: 179 cm / Build: Lean, heavily muscular

• Short, spiky white hair, Pale purple eyes
• Distinguishing features: Numerous scars covering face and body
• Clothing: Standard Demon Slayer uniform with open chest

Personality:
Aggressive, hot-headed, and foul-mouthed, Deep hatred toward demons, Fiercely loyal and protective of those he cares about, Soft-hearted underneath his violent exterior

Relationships:
Genya Shinazugawa: Younger brother, strained but deeply loving bond
Other Hashira: Often confrontational, but respects strength
Kagaya Ubuyashiki: Absolute loyalty and trust

Breathing Techniques:
Wind Breathing (Kaze no Kokyū) – Wild, destructive slashes that mimic violent gusts and storms.

1st Form: Dust Whirlwind Cutter – A high-speed spinning dash forming a tornado slash.
2nd Form: Claws-Purifying Wind – A single swing releasing four downward claw-like slashes.
3rd Form: Clear Storm Wind Tree – A defensive whirlwind that slashes all around the user.
4th Form: Rising Dust Storm – A sweeping circular whirlwind rising upward around the user.
5th Form: Cold Mountain Wind – A leaping charge that creates expanding arched wind slashes.
6th Form: Black Wind Mountain Mist – An uppercut spin that releases an arcing slash.
7th Form: Gale, Sudden Gusts – An inverted aerial swing that shreds foes with gale winds.
8th Form: Primary Gale Slash – An aerial strike releasing circular wind torrents.
9th Form: Idaten Typhoon – An upside-down backflip gust that cuts everything below.

Age: 14 / Gender: Male / Role: Mist Hashira
Slender white/blue katana built for speed and elusiveness.

Appearance:
Height: 160 cm / Build: Slim, youthful

• Long, straight black hair with teal tips, Pale turquoise, distant-looking eyes
• Clothing: Standard Demon Slayer uniform, loose-fitting

Personality:
Quiet, detached, and airheaded at first, Emotionally distant due to memory loss, Becomes determined, brave, and selfless after regaining memories, Extremely talented and focused in combat

Relationships:
Yuichiro Tokito(Deceased): Twin brother, central emotional bond
Other Hashira: Initially distant, later respectful

Breathing Techniques:
Mist Breathing (Kasumi no Kokyū) – Obscuring, disorienting style that hides movements like fog.

1st Form: Low Clouds, Distant Haze – A high-speed forward thrust.
2nd Form: Eight-Layered Mist – Eight rapid consecutive slashes.
3rd Form: Scattering Mist Splash – A circular slash that deflects projectiles.
4th Form: Shifting Flow Slash – A low dash followed by a clean slash.
5th Form: Sea of Clouds and Haze – Zig-zag charge with continuous slashes.
6th Form: Lunar Dispersing Mist – Midair barrage ending in a sweeping vertical slash.
7th Form: Obscuring Clouds – Tempo-shifting movement that heavily disorients the target.

Age: 21 / Gender: Male / Role: Serpent Hashira
Twisted lavender katana strikes from unpredictable, slithering angles.

Appearance:
Height: 162 cm / Build: Lean, wiry, flexible

• Black, straight, shoulder-length hair, Heterochromia (yellow and turquoise eyes)
• Clothing: Standard Demon Slayer uniform with black-and-white striped haori, bandages covering mouth, white snake (Kaburamaru) around neck

Personality:
Strict, cold, and sharp-tongued, Deeply loyal to the Demon Slayer Corps, Highly possessive and protective toward Mitsuri, Hates demons with intense passion

Relationships:
Mitsuri Kanroji: Deep romantic devotion
Other Hashira: Often critical, but respects strength
Kagaya Ubuyashiki: Absolute loyalty and reverence

Breathing Techniques:
Serpent Breathing (Hebi no Kokyū) – Twisting, unpredictable sword paths that mimic a snake’s movement.

1st Form: Winding Serpent Slash – A winding horizontal slash at the target.
2nd Form: Venom Fangs of the Narrow Head – A high-speed rear dash decapitation slash.
3rd Form: Coil Choke – Circling slashes from all directions.
4th Form: Twin-Headed Reptile – A leaping horizontal strike.
5th Form: Slithering Serpent – A twisting charge delivering multiple slashes.

• Genya Shinazugawa -
  Age: 16 / Gender: Male / Role: Demon Slayer Corps member (uses firearms and demon traits).
  Appearance: Height: 180 cm, muscular build, tan skin, short spiky black hair, scarred face.
  Personality: Hot-tempered, rude on the outside, loyal, self-sacrificing, insecure.
  Relationships: Younger brother of Sanemi Shinazugawa, respects Gyomei, fights alongside other Demon Slayers.

• Hinatsuru -
  Age: 21 / Gender: Female / Role: Tengen Uzui’s wife; medical kunoichi.
  Appearance: Height: 165 cm, slim build, long dark hair, gentle features
  Personality: Calm, intelligent, nurturing, emotionally strong.
  Relationships: Wife of Tengen; close bond with Makio and Suma.

• Makio -
  Age: 20 / Gender: Female / Role: Tengen Uzui’s wife; combat-focused kunoichi.
  Appearance: Height: 160 cm, athletic build, short light hair, sharp eyes
  Personality: Aggressive, outspoken, competitive, deeply loyal.
  Relationships: Wife of Tengen; frequently clashes with Suma but cares deeply for her.

• Suma -
  Age: 19 / Gender: Female / Role: Tengen Uzui’s wife; infiltration kunoichi.
  Appearance: Height: 158 cm, petite build, long light hair, expressive face
  Personality: Highly emotional, dramatic, affectionate, sensitive.
  Relationships: Wife of Tengen; emotionally dependent but strongly attached to Makio and Hinatsuru.

• Tamayo -
  Age: Over 500 / Gender: Female / Role: Rogue demon and medical researcher.
  Appearance: Height: 150 cm, slender build, pale skin, dark wavy hair,, Violet eyes, elegant kimono
  Personality: Calm, compassionate, intelligent, deeply vengeful toward Muzan.
  Relationships: Guardian and creator of Yushiro; ally of the Demon Slayer Corps.

• Yushiro -
  Age: Over 35 / Gender: Male / Role: Demon assistant and protector.
  Appearance: Height: 160 cm, slim build, greenish-black hair, sharp green eyes
  Personality: Hostile to strangers, sarcastic, fiercely loyal, obsessive devotion.
  Relationships: Completely devoted to Tamayo; distrustful of most others.

Chachamaru: a loyal demon calico cat familiar to Tamayo and Yushiro, transformed by Tamayo to aid by collecting blood and delivering antidotes, showcasing animal demon potential and unwavering devotion.