Yae is a young girl of moderate height with dark eyes that tilt slightly inwards, framed by thin eyebrows. She has long, dark hair that reaches down her back, parted to the right with a shoulder-length clump hanging down on either side of her face, which she wears tied back in a low bun.
Yae wears a short, patterned yukata which she fastens with a cloth sash and a belt, and a pale-colored animal skin cloak. She sports a pair of pale pants and knee-high boots, and she wears her hunting rifle on a belt around her torso and over her shoulder.
Yae is a stubborn and impatient girl. This shows when the villagers stopped her from going on the mountain to made her revenge and when Shinobu told her about the Demons and the Demon Slayers. But despite Shinobu's warning, Yae went to the mountain and met her father there - as a Demon. She also showed her responsibility to die with her father for caring for him although he turned into a Demon.
Yae dreamed of becoming a Matagi hunter since childhood, but the people around her had doubts as a female Matagi was unheard of. Her father originally shared these thoughts, however he eventually gave in and decided to train her in the ways of hunting on the condition that she always took it seriously. He taught Yae how to survive on a cold mountain and how to hunt large animals such as bears and deer, and use their carcasses effectively.
Before the events of Giyu Tomioka: Gaiden, Yae lost her father to a Demon, who she at first suspected was a bear.
A man from the village is shouting at a Yae for going into the mountains alone again, and she's is protesting that she wasn't alone because she had Taro, her dog, with her. Shinobu Kocho, who had been in a nearby house, emerges and asks what's going on, and the woman explains that Yae is the daughter of a Matagi hunter named Matazo. Yae had been claiming that she'd witnessed her father and friends's death after they'd been attacked by a rumoured bear, and ever since then she'd been heading into the mountains to attempt to seek vengeance.
The gun hanging from Yae's back is suddenly grabbed by a man who's approached her from behind, and the girl whips around, shouting at the man not to touch her gun and attempting to deliver a blow to him with her right elbow. Her arm is stopped by the man, who is revealed to be Giyu Tomioka.
Giyu begins to introduce himself, saying he's with the Demon Slayer Corps and requesting that Yae tell him what she knows about the Demon that had been rampaging around the village. The villagers are confused and eventually begin to tie the Water Hashira up as they fear he's breaking the law. Yae starts to speak, saying that she doesn't know what he wants, but then falls to the floor from a fever before she can finish her sentence.
While unconscious, Yae starts to dream of her childhood. She's playing outside with her dog as her father and another man discuss indoors the fact that Yae wants to become a Matagi. Her father, Matazo, says that he told her hunting is a game and that he's never heard of a female Matagi before, but the other man argues that Yae must be lonely at home since there aren't any other kids for her to play with. He says that she must just want to be with Matazo, asking him to understand her feelings.
Matazo exits the house and walks up to Yae and Taro, saying that if she messes around with the gun he's taking is back, and Yae smiles widely.
Yae's childhood flashback ends, and another begins, showcasing the time Yae found her family and friends had been murdered. She gasps, asking how and why this could happen, and then looks up and sees someone eating one of the bodies, calling "Father?" out to him. Yae and her father's eyes meet, but all she sees is a man-eating bear.
When Yae awakens, she finds herself in a bed in the pharmacy on the other side of her village. She opens her eyes to find Shinobu sat close to her, bending down with her face near hers, and she blushes and cries out when she sees her. Yae sits up and moves away, clutching her gun, and Shinobu laughs, asking her to please not shoot her. Shinobu explains the situation, telling Yae her location and the fact that she was unconscious for half a day, then offering her herbal medicine and saying that she can't avenge anyone while in her current state. Yae takes the medicine, asking what's in it, but Shinobu just tells her to drink it.
The Insect Hashira then turns to Yae, offering her condolences for the girl's father's passing and asking her if she could question her about the incident. She explains that whatever attacked them could be a Demon, and then Giyu, from where he's sitting in the other room, interrupts and says that he should do the explaining. Shinobu reminds him that he's being attacked, and, after some protesting from him, Shinobu gets Giyu to back off.
Yae and Shinobu's conversation continues, and, after telling Shinobu what she knows about the bear, Yae says it's her turn to ask questions. She asks what a Demon is and what Demon Slayers are, to which Shinobu explains the basics of what makes a Demon, including the regeneration, strength, lifespan and the two ways to kill it, and the Demon Slaying Corps that purge Demons from the world. Yae asks if they slaughter Demons, and Shinobu tells her not to phrase it like they're executing people since all they're doing is ridding the world from evil Demons.
Shinobu then says that she must have been wrong about Yae's case, since the attacker seems to genuinely be a bear, but still offers her her's and Giyu's help to hunt the bear. Yae simply says that she's a Matagi, so she can do her own avenging.
Yae then gets ready to leave, thanking Shinobu for taking care of her and ignoring the Hashira's protests that she still needs to rest. As she makes her way towards the door of the pharmacy, Giyu walks over to her and stand before her. He advises her not to walk around at night, but Yae hot-headedly replies that there aren't any Demons around and there's nothing wrong with a Matagi shooting down a pest. Giyu asks her why she's going into the mountains to avenge someone and asks her if she's hiding something from them. Yae shouts out that he's annoying, and pushes past him to get to the door. Just before she's gone, Giyu tells her that, at the very least, he's never seen a Demon turn back to a human.
Yae ventures out onto the snowy mountains with Taro, crouching down and paying her respects at the pile of sticks that used to be her home. As they walk, Yae tells her dog to follow the smell, crouching down next to him, stroking him and telling him to keep pushing despite the freezing cold. Yae remembers her father again, and the time that he spent teaching her the skills needed to become a Matagi. They were sitting next to a bear they had just taken down, and her father was telling Yae never to waste a part of a bear because every part was a blessing of the mountain. He says that they as Matagi live off what the mountain gives them, and that, because they kill, they have to live.
The flashback ends, and Taro begins barking at something, running off ahead of Yae to investigate it. She calls after him, and then sees something fly backwards towards her and fall onto the snow. Shocked, she realizes it's Taro's decapitated head, and moves on forwards to reach the top of the hill. On the other side, she sees a figure. Yae knows immediately that it's the man that was once her father, bent over the corpse of Taro, and thinks to herself that he really did become a Demon.
Readying her gun, Yae remembers the shooting lessons her father gave her, getting into position to fire at him. She thinks about how she wanted it to be a mistake, and the fact that she lied about her Demon father being a man-eating bear, but Taro's death was the last straw. Yae pulls the trigger, blowing her father's head off. As the Demon begins to recover, regenerating his head and running towards her, she asks in her mind how he became a Demon and why he had to kill everyone. Aiming her gun at him again, she silently asks why he fled from their house like he was running away.
Matazo jumps on Yae, pinning her down, and she slams her gun side-on in his mouth to gag him. Yae thinks that she will shoot him if he can't turn back, and then asks him aloud, as she begins to cry, why he didn't eat her as well that day. The Demon begins to say something, and suddenly is leaped on from behind. Giyu appears, swinging his sword at the Demon, who leaps away from Yae, one arm severed. He stands between Yae and the Demon, Shinobu standing behind them both and whispering to Yae over her shoulder what a coincidence this was.
Yae thinks back to the first time she went hunting and her father helped her out but said it was the only time he would do so, saying she had to learn how to do it herself. She happily says she knows and quotes a line her father used to say, that because they killed they had to live and her father had nodded approvingly.
Back in the present, her father, now a Demon who had lost his left arm and foot, is struggling to make his way towards her and the two Hashira in the harsh snow. Yae looks on in horror and Giyu tells Shinobu to look after her as he moves forward to deal with the threat. Shinobu jauntily asks Giyu if he is sure and offers to kill the Demon with her poison as she draws her blade. The words carved into the side of blade strike fear into Yae and she asks both the Hashira to wait.
Shinobu looks at her in shock and Giyu asks her what the matter is now, saying that she knows that the demon in front of them was longer the father she used to know. The Demon begins to regenerate his lost limbs and Giyu charges at him to finish him off. Attacking the Water Hashira, the Demon grows a projectile of his own bone and throws it at Giyu who shatters it with a block from his blade. This was but a diversionary tactic however, as the demon used this time to get up close to Giyu and attempts to stab him with a sharp outgrowth of bone from his forearm. Giyu is able to dodge the attack however and Yae looks on in horror and dismay as he beheads her father with a Water Breathing: Fourth Form - Striking Tide, killing him.
The dismembered head weakly mutters something as it remembers Yae in its final moments and Giyu is puzzled but declares that it is over. Shinobu looks at Yae in concern as the girl repeats those words and points her hunting rifle at her throat. Giyu yells at Shinobu and rushes forward to protect Yae. Shinobu worries that she won't be able to get there in time, but miraculously, Yae's rifle jams, and Shinobu tackles her before she is able to pull the trigger. Yae begins to cry and asks why they won't let her do so Shinobu looks at her with a pained and sorrowful expression.
Crying that she has lost everything now, including her home, she says that the Demon Slayers don't understand a thing and for them to leave her alone. Giyu walks up to her and tells her that her father's final words were probably meant for her and that before passing he had whispered simply, "Live". Still crying and utterly confused, Yae breaks into a smile and can only exclaim at Giyu's words. Saying that he does not care about her grumbles about Demons as it has nothing to do with him, Giyu walks off. Shinobu calls for him but he continues to trudge off and tells her not to forget that they are Hashira. Disapproving and unable to leave the girl without some words of comfort, Shinobu tells her to bear with her feelings as that was how the rest of them had managed to continue on as well.
As the Hashira leave and the snow stops, Yae looks on at the serene landscape and picks up the hunting rifle and notices that there are blood stains all over the trigger. She realizes that her father's blood had hardened on it, preventing the trigger from being pulled earlier when she attempted to commit suicide. The sun comes out and as the blood begins to disintegrate away in the light Yae smiles as she ponders over the words of her father and the final message passed on to her by Giyu, hugging the rifle as she watches the sunrise.
Yae, finding peace, proceeds to create a grave for her father and Taro, pay her final respects to them, before once again setting out to live on as her father wanted.
Abilities and Powers
Yae was trained by her father, Matazo, in the skill of hunting since her early childhood. As such, Yae has shown herself to be skilled in tracking, hiking, climbing and maneuvering through mountain terrains with ease, as well as hunting large animals such as deer and bears with her hunting rifle. As a result of her tracking skills, she was later able to track down even a Demon through a snowy mountain.