Name: Rei Yūrenagi
Age: 18 (at the start of the anime) 21 (at the final battle)
Gender: Female
Sexuality: Straight
Species: Yōkai (a species similar to demons however can walk in the sun, change into how they would look like as humans or have one characteristic that indicates what type of Yōkai they are, powers aren't based around using blood, can eat food, protects and help humans thrived ever since before Kibutsuji became a demon, are against eating humans but if one does they will slowly be unable to walk under the sun, and can only be killed by wisteria poison infused with red spider lilies or by (only) Muzan's poison)
Height: 5'0"
Personality: Kind-hearted, headstrong, has a motherly personality, and is sympathetic to demons. Don't take advantage of her sympathy because she doesn't hesitate to kill to free people from their suffering if they want. Don't let her kind personality fool you for she can be scary when she is protective of her family, friends, and comrades. She is extremely patient when it comes to training or waiting for something to arrive.
Affiliation: Good
Occupation: Yōkai Demon Slayer (the Yōkai Demon Slayer organization consisting of its members being Yōkai and they protect the Demon Slayers from a hybrid species of demon and yōkai called Yōkai Demons (who are mostly similar to Yōkai but when they're under the sun they will change into how they use to look like when they were humans and cannot use their Demon Art). Their leader is not Kibutsuji but his daughter Kurai who is hellbent on killing Kibutsuji for murdering her four older sisters and made her mother Reiki Kitsunami (who is a kitsune Yōkai and was Kibutsuji's Yōkai) go into depression and eventually commit seppuku) and Yōkai Guardian (Leader of the Yōkai and most powerful Yōkai known to have the abilities of every Yōkai but Rei became the new Yōkai Guardian at a young age meaning that she hasn't have enough training to be the strongest but can last long in battle)
Breathing Technique: Ghost Breathing
Nichirin weapon: Dual Katanas
Blade color: Cyan
Family:
- Mother: Emiko Yūrenagi (Former Ice Yōkai Hashira)
- Father: Daisuke Yūrenagi (Former Yōkai Guardian and Former Ghost Yōkai Hashira)
- Brother: Akiro Yūrenagi (Wind/Battle Yōkai Hashira)
- Sister: Yuki (Adopted sister) (Former Tsuguko of Emiko)
Likes: White rice, steak, shrimp, lavenders (their aroma), drinking lavender tea, her friends,, children, protecting her family, bringing peace, Tsukikage Tsuki Tsugikuni, giving others a second chance to redeem,
Dislikes: Muzan Kibutsuji, abusers, Kurai inflicting suffering on others.
Love Interest: Tsukikage Tsuki (Tsugikuni)
Looks: She has cyan faded to white hair in a high ponytail braid along with turquoise blue eyes and light color skin. She wears a short sleeved short white kimono lined with purple fluff along with a cyan colored obi belt and black bindings around her chest as well as wears a pair of purple faded to blue short kimono pants that are above the knees. Rei tends to not wear shoes, but when she does, she wears black tabi sock with purple zori sandals with white straps. She occasionally wears a haori similar to the what Rengoku wore but the flame part is cyan which is supposed to give off a ghost vibe. She has two katanas strapped to her at the waist, along with kunai blades and a sword on her back with the blade looking similar to Shinobu's. She also has two small daggers in their sheathes which she has strapped to her lower legs in case.
Backstory: Rei was born into a family of creatures called Yōkai. She was educated by her parents who taught her swordsmanship, how to make medicine, how to heal wounds, and how to use her Yōkai abilities. Her older brother Akiro (who is a martial artist and was taught by his father) taught her martial arts to be able to defend herself in case she is separated from her sword. At the age of 13, her mother was put on trial because Yuki willingly became a Yōkai Demon. Emiko committed seppuku but the dagger was pulled out by Glacier Yukioboro (who is Emiko's other tsuguko). Daisuke tried to defend her but instead decided to be punished by having himself become a stone statue (it's another option of how the Yōkai will be punished besides seppuku. But it is also a way to have their bodies preserved to be remembered but only those who are Yōkai Hashira or heroes can choose to do the second option). Akiro went missing after the trial resulting in Rei being alone. At the age of 14, she met Tsukikage when he was cutting wood for his brother Hikaru and his mother Luna Tsuki who is a former Yōkai Hashira who uses Shadow Breathing. Rei was taken in and helped Luna train Tsukikage and Hikaru to use a sword. At the age of 16, Luna Tsuki was killed by Kurai resulting in Tsukikage, Hikaru, and Rei being taken in by Kagaya Ubuyashiki's Yōkai name Amari Amekami who has the same curse as Kagaya but instead of losing her sight she loses her hearing. Hikaru and Tsukikage learnt sign language to communicate with Amari and at every Yōkai Hashira meeting, Rei voluntarily joins in the meetings to be Amari's interpreter. At the age of 18, Hikaru, Tsukikage and Rei decided to join the organization to stop Kurai and help the Demon Slayer Corps to defeat Muzan.
Ghost Breathing
1. Ghost Breathing: First Form: Ghost Slash (Yūrei no kokyū: Ichi no kata: Yūrei Giri)
* First Form: Ghost Cutter (Ichi no kata: Yūrei Kattā)
2. Ghost Breathing: Second Form: Ghost Will o' Wisps (Yūrei no kokyū: Ni no kata: Yūrei)
3. Ghost Breathing: Third Form: Soul's Rebirth, Redemption (Yūrei no kokyū: San no kata: Tamashī no saisei)
- This form is based on Water Breathing Fifth Form: Blessed Rain After The Drought. However the user turns the demon back into a human but the target will maintain their demon art, regeneration, and not be able to die when their heads are cut off or poisoned)
* Third Form: Soul's Rebirth, Reincarnation (San no kata: Tamashī no saisei - Umarekawari)
- This variation sets the target's soul free from their sins of taking their victims' lives away. This form gives the target a chance of being reincarnated.
4. Ghost Breathing: Fourth form: Yōkai's Fury (Yūrei no kokyū: Shi no kata: Yōkai no ikari)
* Yōkai's Fury, Foolish Trickery, Kitsune (Yōkai no ikari, Kitsune)
* The tip of the blade will be covered in flames as the user creates a flurry of slashes at the target and then dashed towards them within their line of view and slash the neck. The slashes looks like they've missed but once the user sheathed their blades, the demon's body with fall apart in pieces revealing that the attacks didn't miss.
* Yōkai's Fury, Raging Gusts of Mountainous Wind, Tengu
* (requires the user to know Wind Breathing) (Yōkai no ikari, Tengu)
* Yōkai's Fury, Arachne's Wrathful Web, Jorōgumo (Yōkai no ikari, Jorōgumo)
* The user creates a series of slashes which forms a web creating a net
* Yōkai's Fury, Wrathful Scissor Cuts, Kuchisake-onna (Yōkai no ikari, Kuchisake)
* requires two katanas as the user must position their arms in a similar pose when using Beast Breathing: Third Fang: Devour but to create a scissor like cut)
* Yōkai's Fury, Piercing Frozen Heart, Yuki-onna (Yōkai no ikari, Yuki-onna)
* The user's nichirin blade will be covered in ice as the user thrusts their blade with the tip of their blade striking the heart making the target freeze into an ice statue.
* Yōkai's Fury, Rising Ashes, Phoenix (requires the user to know Flame Breathing) (Yōkai no ikari, Fenikkusu)
* The blade becomes covered in flames as the user unleashes two fiery slashes. First, a vertical slash and the second being a horizontal slash but upwards
* Yōkai's Fury, Sickled Ambush, Kamaitachi
- requires two katanas) (Yōkai no ikari, Kamaitachi)
* Yōkai's Fury, Aquatic Wrath, Mizuchi
* requires the user to know Water Breathing) (Yōkai no ikari, Mizuchi)
* Yōkai's Fury, Quaking Wrath, Namazu (Yōkai no ikari, Namazu)
* Requires user to know stone breathing
* Yōkai's Fury, Slithering Ambush, Nure-onna
* requires the user to know Serpent Breathing) (Yōkai no ikari, Nure-onna)
5. Ghost Breathing: Fifth Form: Soul's Ethereal Nightmare (Yūrei no kokyū: Go no kata: Tamashī no eien no akumu)
6. Ghost Breathing: Sixth form: Reaper's Curse (Yūrei no kokyū: Roku no kata: Karito no noroi)
7. Ghost Breathing: Seventh form: Wrath of the Vengeful Ghosts (Yūrei no kokyū: Shichi no kata: Onryō no ikari)
* Note: Seventh Form: Wrath of the Vengeful Ghosts is an exclusive form of Ghost Breathing for the user needs to be a Yōkai (which are similar to demons but they feed on demon flesh/blood and resist the sun; however, when they sniff pollen from a wisteria flower, they act like how a cat would act when they sniff or eat catnip), gain the demon slayer mark even if it's temporary, have the ability to see ghosts, or a member of the Flame Family by blood.
* Note 2: Reiya, the creator of Ghost Breathing, claimed that this form is similar to Breath of the Moon: Eighth Form: Moon-Dragon Ringtail but the blades are shaped like emblems that resembles a yōkai.
8. Ghost Breathing: Final Form: Ethereal Ghosts of Eternal Darkest Nights (Yūrei no kokyū: Tsui no kata:
* The user will jump into the air or kick themselves off a wall to unleash a flurry of slashes from the air, then release a huge attack which the user dash towards the target with their nichirin weapon ready while the user is surrounded by a ghostly aura and ghost energy which then shapes itself into a dragon. Once the user strikes the target, the attacks will unleash a cyan colored fiery tornado.
* Note 1: Whenever Rei Yūrenagi used this final form, she would always do a backflip out of the tornado and does a similar pose that Kyojuro Rengoku, the Flame Hashira, does after he uses Flame Breathing: Ninth Form: Rengoku.
* Note 2: The Final Form is an esoteric art exclusive to the Yōkai Guardians who are known to be associated with Yōkai.
* Reason is that the first time it was performed by someone who wasn't a Yōkai Guardian, the Ghost Breathing user ended up retiring as the final form made the user feel like their lungs exploded and made them unable to breathe as they felt like their life source was being drained by spirits.
