Demon Slayer Corps, an organization that had existed since ancient times, to fight against the Demons and protect the humans from them. Their base was secret; even though she came here, she wasn't familiar with the surrounding geography and had no idea where it was, but even if she did, not everyone knew.

During the time she spent with Shinobu, the Hashira, she learned of the rankings in this world when one became a Demon Slayer; by completing the Final Selection, they were granted the Rank of Mizunoto.

Ai sat near the window, looking out from the first floor where her room was, at the courtyard and a few people training. Soon, her training would start too. She flicked her finger up, and a virtual screen that only she could see appeared.

Her father's avatar hadn't appeared since the first time, but there was one tab other than her name and race.

Ranks, and when she clicked it, she could see the Ten Ranks, Mizunoto, Mizunoe, Kanoto, Kanae, Tsuchinoto, Tsuchinoe, Hinoto, Hinoe, Kinoto, Kinoe. And above these ten ranks, there were a group of elites, second only to the organization's leader, the Hashira, and the one who came to pick her up was a Hashira.

"That speaks volumes," Ai closed her eyes, resting her cheek on her palm, tracing her bangs, hiding her scarlet eye.

She opened her eye to look at her rank, only to find a line at the bottom.

[You are not even worthy of getting a rank.]

"Idiot Dad," Ai giggled to herself, and that joyful laugh turned into a sigh. It wasn't that she was weak, but none of her abilities were available since there was no chakra here, and surprisingly her body wasn't producing any.

If she had to wonder, it was because the physical and magical laws were different.

She heard of the breaths, the Way of Breathing, and how there were so many breaths.

Everything originated from the Five Elements, much like what happened in her village, from Fire, Water, Stone, Thunder, and Wind.

The thing that surprised her was that it was Stone, not Earth. Although she had mastery of all five, her main Elements were Earth and Water, and it seemed that combining the two Elements here was much easier, and even finding its Conceptual Derivatives like Love.

She bit her lips, shaking her ankle impatiently, feeling her breath had stopped. She puffed her cheeks for a while before standing up in annoyance, "Ugh…damn it…I am enjoying the thought too much. I hate you, Dad. I hope Mom beat you a lot."

Even while spouting all that, she happily bounced down the stairs, stopping in front of the courtyard. Her green eye fixed on the girl that was practicing in front of her, although she was mostly quiet, and she didn't know her name, "Lady Shinobu said that you'd teach me? Hello, my name is Ai Senju."

The girl with large gentle eyes of dark lilac eyes, covered with thick eyelashes, blinked at her, wordlessly nodding, and took her to the dojo inside. She went to the corner, taking two wooden swords before walking back and giving her one.

Ai looked confused and held it as the silent girl showed her by holding her own. Ai copied what she did since there were times when she learned Kenjutsu, even though she liked fighting with her fists and legs. 

The silent girl's stoic face was betrayed by surprise she felt, telling Ai that she had heard details about her, and then it disappeared.

There was much she taught her; some things were similar, some were different because of the breathing, and since her breathing style wasn't decided, she was taught all the basics.

She did it for a few days, and then she started learning about the breaths, how the breathing styles were different, and what she wanted to do was observe the most basic ones: the Fire, Wind, Stone, Water, and Thunder.

"You want to observe them? Not learn them?"

Ai tilted her head, "It's the same for me? I can learn by observing…."

"Oh," Shinobu took a step forward, looking up at the girl already taller than her, had curves in the right places, and was probably still years from maturing. She traced her cheek, gazing into her green eye, "Through eyes?"

Ai blinked in wonder if she could even call it the eyes. Even when she was in her world, she had two, or it could be said three, bloodline limits. One she got from her mother's side, the other she got from her father's physique, and then the actual ability that every one of her father's children got, unique to them, the one that rested in her scarlet eyes.

It wasn't active; instead, she could tell her body was too weak to handle the load. But it came with passive abilities, like being able to see more than a person should, the path of their energy, their lifeforce. She thought it had something to do with her mother's side affecting her inherited ability.

"Oh, then I can talk, and if Master supports it, you could find teachers. Which style do you want to start with?"

"Water Style. I want to see a Water Style User," Ai eagerly asked since even seeing one of the main elements would help her compare with Water Style she was used to.

"Oh, that one," Shinobu looked down for a bit, "I'll ask if there is anyone that will teach you that Style."

"Yes," Ai continued her training with Kanao for a few days before she finally got the green light, and Kanao was sent with her to guide her and protect her.

Along the way, her chirpiness came back after becoming comfortable while living in this world for months, and she kept talking to Kanao, even though she didn't talk back much.

"Say, Kanao, where are we going? Who are we going to meet? Is it someone you know?"

She wasn't expecting a reply and was about to continue talking when Kanao replied to her.

"Sakonji Urokodaki. He was a Hashira in the past and has since retired. Now he is the main cultivator; he's the one that has taught the current Water Hashira and all others."

"Oh, you talked!!" Ai jumped over the short girl, hanging on her, hugging her tightly, "Your voice is so nice to hear! You should talk more!"

Kanao's footsteps stopped as she looked at the young girl, taller, bright, and warm, and looked away. She kept walking, dragging Ai Senju's body despite the difference in size.

Ai's face became lax as a smile appeared across her lips, "Oh, this is so much better."

Kanao stopped again, pushing her face away, "Walk."

"Yes, Ma'am," Ai grinned, walking beside her, traveling for days before they reached the foot of the mountain where this Ex-Hashira Sakonji Urokodaki lived.

The two of them stood out of the house, and Ai looked around, impatient, when the door opened, and an older man wearing a red tengu mask covered his whole face.

"Welcome, both of you. I got the letter from the Master," He said in a gentle voice, looking towards Ai from behind the mask, "Ai Senju, I assume? You are the same as he described."

"Sorry for all the trouble I will cause you," Ai politely bowed, holding the bag straps.

"Come in."

Urokodaki invited them in, sitting down on the other side of the low table and pouring tea. He observed Ai as she silently drank, relaxing.

"Why do you want to learn the Water Style?"

Ai held the teacup in her hand, staring at her reflection in the rippling tea, "How do…other people decide which one is the best for them?"

"For most, they learn depending on who introduces them to whom. The boy I am currently teaching was found and saved by the Water Hashira, and he was introduced to me. Which is why he is learning the Water Style, but you chose Water Style? Any particular reason?"

Ai parted her lips, closing them, "An ancient legend…well, not so ancient, but it's a part of my family, my mother's side. Her grandfather was said to hold immense life force and power. People told stories of how he could control wood and had overwhelming power. Mother said…it was the Water and Earth, and when you combine them, you get the Wood, although she also said that Great Grandfather was special, and no one could compete with his Wood-Style, even if someone else managed to master it. At that time, I didn't know about these Demons and Demon Slayers…but now I have a chance. I want to see if I can do it. wield the Wood Style."

"Oh, your family has a history of Demon Slayers, too," Urokodaki was slightly surprised to hear that Breathing Styles had left this land, too, since they were protected. Maybe it was hubris to think they hadn't discovered this power in other lands.

"Not exactly…they were Shinobi."

"Shinobi," Urokodaki raised his voice with a bit of surprise, smiling, "Ah, there is someone in Hashira that would love to know that. Anyway, I won't ask you much more. If you want to learn, then I will teach. For today, rest in the house that was made for you two next to this."

"Oh," Ai's fleeting gaze went to the girl lying in the center of the living room, and she sniffed, feeling a familiar scent that she got from Tamayo.

She didn't say anything but bowed and left with the silent Kanao, spending the night in the next room over, and finally, it was the day where she got what she wanted.

He tested her skills, which she brilliantly passed, and then she sat down cross-legged, showing the way he breathed, the water breathing.

Ai sat in front of him, observing, and there was a glow in her right eye, the scarlet one, hidden by the golden blonde hair. She saw his life force coming out from every pore and the way of water, the breaths forming away.

Unconsciously, she started doing the same, the breathing that he was doing, copying every movement of his muscles. The muscle in her fingers trembled, her wrist, forearm, waist, under the mass, and she got used to it.

When she felt the energy produced by the breathing inside her, she realized that many pathways were similar to when she used the Water Chakra. But there were many moves; one pathway was divided from one Jutsu. So she started remembering the feelings she had when she used those Jutsu, marking the common pathways.

She abruptly stood up, rushed inside her room, and took out a journal and pen from her things, lying on the floor beside it. Her hand moved, drawing the structure of the pathways inside her, and then she drew the pathway of one Jutsu.

She moved on to the next page, ignoring the footsteps she heard coming closer, and drew the next one, and then next, and another. One hour passed, and then the next, but neither of the two sitting beside her disturbed her.

Instead, Urokodaki watched it with interest, watching her work, and then once she was done with that, she drew his body, pathways, and the method through which he breathed and drew his Way of Breathing.

She closed the journal once she was done, flipping through the pages with a dazed look. After hours and hours of doing all that, now she said, "I see it…."

"See what?"

"I can't master Wood Style now, but I finally see how I will fight and what kind of katana I will wield. I see my fighting style…." Ai turned around, lying on her back with a hazy look in her eyes as she sat up and turned towards Urokodaki, "I apologize for stopping in between. Can we please continue?"

Urokodaki glanced towards Journal but didn't ask and continued her training. He was amazed that she learned breathing so quickly, but seeing her work, the drawings, she knew of it, and knowledge different from theirs.

There was a smile under his mask, maybe slightly happier than he had been in years, thinking about what she came up with. Although he skipped the basic training, he was starting to get curious, so he asked her to climb the mountain filled with traps and reach back to the house at the foothills, and she did it in one hour.

"I see; you have had training."

"Yes, plenty of that," Ai grinned, cracking her fingers, "So you don't have to worry about anything; throw the hardest tests at me, and I will be successful."

"Good then," Urokodaki taught her for another few weeks when something happened that caught his attention. The other student he was currently teaching cut through the enormous boulder, the one he thought he wouldn't be able, and that meant suggesting him for the Final Selection.

And one other thing happened at the same time, "Right here. The Nichirin Sword you ordered is here."

Usually, everyone got the same Nichirin Sword, the metal they were made from absorbed sunlight, which allowed them to kill the Demon when decapitated from it.

But Ai didn't just ask for one, she drew one, giving the schematics, and in return, she was ready to share her drawing, the pathways to her techniques.

He refused and still made sure she got the weapon she needed, and it was different from most Nichirin Sword. Only a few got such treatment.

Still, the weapon's design she wanted was attractive, and some of the Blacksmiths liked it. It was a Nichirin Sword but not a Katana; instead, it was in a scissor shape; it formed a broad sword, double-edged when put together.

Ai Senju took the sword, which was nebulous purple, from the hilt to the tip. She took a deep breath, using Water Breathing Technique, and the blades of the scissor-shaped sword turned bluish, and when she let go, they turned back.

"I love them; thank you so much."

Urokodaki smiled at her, but then the smile disappeared. He guided her to the top of the mountain, massive, more prominent than even her height in front of the boulder. A boy with black to red hair stood before the boulder, successfully cutting it apart into two.

Urokodaki stood with the two, watching the boulder, "I didn't think you could split it….I didn't want you to…."

"Huh?" Tanjiro looked at him in surprise, and Ai wondered why he would say that.

Urokodaki turned to stroke his head, "I didn't want to send you to the Final Selection. I didn't want to send another child to death. But you split the rock…you did well, Tanjiro. You are an amazing child."

Tanjiro hugged him back with tears before the two separated, "Now, let's get you ready to send you to the Final Selection."

"Hey, Teacher! I want to go to the Final Selection too!"

Urokodaki smiled, looking back towards her while Tanjiro confusedly tried to figure out who she was, "It took this one six months to cut this into two. When you can do that, then you can go. Although…"

Ai couldn't hear what he was saying; her mind blanked out. She took the broadsword in her hand, watching the boulder.

She heard it, a heartbeat, and she slashed down, cutting the already cut boulder, and its four pieces fell. She breathed, grinning, "See, I did it. I told you I had training in these things?"

"Oh, you had training," Tanjiro relieved, patting his chest, "Otherwise, it would have been demotivating."

Urokodaki sighed, "Fine; if both of you can do that, you are allowed to go. First, allow me to cut his hair, and then you leave together."

"Thank you!"

Ai faced Tanjiro, grinning, "It seems we'll be traveling together."

"So it seems," Tanjiro smiled, feeling the airflow brush past them.