Yoshiwara,

A town of night, awash in vanity, desire, love, and hate. As its name suggests, the Hanamachi Entertainment District is a specialized selection of towns. Most of the Courtesans here were sold into service due to poverty and debt. So they bear many hardships. They now have clothing, food, and shelter, and if they succeed as Courtesans, a wealthy man may yet buy their freedom. 

An Oiran, the Highest Rank among the Courtesans, is a remarkable woman who has everything; beauty, education, and artistry. An Oiran ranks high in status, so it can be challenging to meet one. Men compete with each other to gain the attention of an Oiran. 

And currently, Ai was roaming in this place, while the Sound Hashira dressed the three boys as a girl and took them to sell to the three houses, Tokito House, Ogimoto House, and Kyogoku House. 

The Sound Hashira was different from other Hashira’s; he was a Ninja, so he lived in the Grey Area. To the point, he even sent his three wives undercover to become Courtesan so they could gather information about the Demons. 

The Ninjas in this world were different from hers, vastly so in some manners, hopefully. She shook her head, removing those thoughts from her mind. According to Tamayo’s information, there was a Demon here, not just any Demon, one of the Upper Ranks. 

Although Tanjiro, Zenitsu, and Inosuke could fight against the Lower Rank Demons, they could barely survive against an Upper-Rank One. Tanjiro could, but with the increase in strength, he had lost Nezuko, who had already taken the drug that would turn her human. 

As for why she was roaming freely on the streets and not working? When she asked Tengen Uzui to put her to work, this was the reply he gave her. 

“There is no way I can put a beautiful woman like you in a place like that. You’d be eaten up before you know it.” 

Although that was sweet to hear and all, she was best suited for the job from her point of view. Not only was she a good look, but she also could create illusions with the recent Breathing Techniques she had learned. 

There is no way any of the humans here would even lay their hands on her, and she could collect the most information possible; why was she here? Why wasn’t she working? 

“It’s more fun seeing them dressed like a girl,” Ai chuckled to herself, “I will enjoy their torment.” 

She rested her palm on her cheek, “Oh my, I am acting like my father now.” 

There wasn’t much to do in this place, so she took a house and started training with her Breathing Techniques, sharpening her senses. 

Once warmed up, she breathed out, “Now that I am warmed enough, let’s see if I can find a Demon.” 

“Wood Breathing Technique. Formless. Enhanced Senses.” 

The technique was simple, it spread out her senses in all directions, but usually, they weakened. To keep them on the same level, she needed certain circumstances. 

About a hundred meters from her, every time she came across a flower, plant, pot, weed, or anything, it spread out a hundred meters more, and if there was another, another hundred. 

Since flowers were used to adorn women in this place, making them more beautiful, they kept a pot or two at every house, some to sell, the other to decorate the garden or house. 

It helped spread her senses out, so far out that she almost had all of the city in her grasp. 

“Right there,” Her senses fixed on one point, finding something different than ordinary, 

There was a woman in the grasp of sashes wrapped around her whole body, sashes originating from the woman standing in front of her, holding many letters in her hands. 

She furrowed her brows, “Um… let’s see… his wife…and the Demon.” 

“Damn it, that is too soon,” She wasn’t expecting to find the Upper-Rank Demon so soon. Even if she were to find it, she could keep an eye on it unless it did something to harm an innocent. 

The problem was that she had no idea if she should even interrupt right now. Not that she wasn’t running through the roofs to get there as soon as possible, to save the woman taken by the Demon. 

But at the same time, her mind was starting to wonder when she looked around; there were too many people. Be it on the train or after that when they came across the Third Upper-Rank Demon. The amount of collateral damage was immense. 

Moreover, the Demon could effortlessly control several sashes to fight in such a city. The number of casualties would go up as the fight goes up. 

“Saving one…or saving many….” Ai stopped on top of the next roof, looking towards the window, the Demon inside. 

A smile appeared on her lips, and she broke through the window, cutting through the sashes, stepping in front of one of Uzui’s wives, “And the right answer is…I’ll save everyone!” 

“Hm?” 

The Demon was a tall, curvy, pale-skinned, slender woman with lime green eyes and long eyelashes. She raised her chin and arrogantly looked at the girl who entered her room, holding a sword, “What the hell are you babbling about?” 

Ai stabbed the ground with her sword, narrowing her eyes, “Wood Breathing Technique: Eleventh Form: Final Prison.” 

“Huh,” The Upper-Rank Demon hastily ran her eyes towards the ground, only to find it quiver before everything broke apart, and thick tree roots rushed up, piercing through everything, even her sashes apart. 

*Cough*Cough*

“Demon *Cough* Slayer?” 

The young woman of average height possesses a voluptuous figure with pale skin and large golden brown eyes framed by eyelashes with prominent ones present on both the upper and lower lashes and thin eyebrows arching downward, which gives her a determined and headstrong look. Her black hair is tied up with golden-brown bangs which hang loosely, framing her face.

She had a haggard expression but determined eyes as she looked at Ai from between the tree roots. 

Ai looked over her shoulder, “I can only hold her for so long. If I die…the prison will break. So evacuate everyone.” 

“YOU BITCHHH!!!!!!!!!!!!!!!!!” 

*THUMP* 

One of the three wives, Maiko, widened her eyes as the prison closed, forming a boulder-sized ball that broke through the roof, forming a crater. 

She swung in the air, turning, landing on her feet, touching the so-called prison, and her eyes widened, ‘Too thick…even though it’s a defensive ability…I can feel so much power coursing through it.’

“Evacuate…we need to evacuate, and send the signal to any other Demon Slayer in the city!” 

“What? Why is that thing here?!” 

Maiko glanced toward the girl that entered her sight, “Ughk! So ugly!” 

“Nooo~!!!!!” Zenitsu held his heart, falling forward. He looked up towards the massive ball of wood, wiping his face of the makeup, “What is going on? Why is Ai here?” 

Maiko remembered, “Right, she trapped a Demon inside there! And a strong one at that, probably an Upper-Rank Demon!” 

“Damn it! I need to warn Tanjiro and Inosuke! And that sound guy!” 

“Sound guy? You mean Tengu is here!” 
Zenitsu pouted, crossing his arm, “Yes…he is…wait…there is an Upper Demon here, right?” 

He felt his legs tremble, panicking, “Right! I should call everyone before it breaks out!” 
“Oye…” Maiko turned solemn, narrowing her eyes, “That girl said…it would open only when she is dead?” 

Zenitsu stopped from the sudden shock, widening his eyes, feeling as if Demon had grasped his heart, and his mind went black. His eyes closed as if he were asleep, “Thunder Breathing: First Form: Eight Fold!” 

She dashed forward, becoming a beam of thunder and lightning, attacking the Prison from eight sides in one moment, and he came to a stop without being able to put a scratch. 

“Thunder Breathing: First Form! Eight-Fold!” 
This time rather than attacking eight different places, he attacked one and managed to create a cut, but it healed the next moment. 

Maiko widened her eyes, realizing it was so impossible to break this technique, not unless you killed the core, the girl at its center. 

Tanjiro, Inosuke, and Tengen Uzui heard the thundering sound and flashed in different parts of the city. It was enough to tell them, “It became flashy too soon.” 

Tengen, Inosuke, and Tanjiro jumped up to rush in the direction, but they stopped the next, being in the same dilemma, “Weapons…we don’t have any.” 

“Shit, hold right there! I’ll be right there!” 

Inside the Wood Prison, 

“What the hell is this place! I can’t seem to get out!” 
Ai stood in the darkness; there was no speck of light in this place. On top of her Enhanced Senses, her vampiric physique allowed her to see even now. The Demon in front of her was combining multiple sashes, flailing around, and she was effortlessly able to block all of them. 
Two things troubled her more than ever; this move had two weaknesses. 

Weakness number one, she had to stay inside and supply it with power. Since she was inside, the first touch of her energy strengthened the inner wall, then moved outward, strengthening others, which supported the inner one, keeping it from breaking. Even if it broke, it was healing first, and so it would create a much stronger prison than one she could create from outside. 

If she passed energy from the outside, the outer wall would be strong, but the inner one would be weak and break apart first, and the one inside could easily chip away since it would be the last to heal, hence breaking the prison quickly. 

This led to the first weakness of this move; if she were killed, the prison would unfold. 

Since this was made using Wood Breathing and Sealing Techniques, the second weakness sealed even light outside, let alone the wind and air. Since she had to breathe for Wood Breathing Technique, it would become undone when she ran out of air. 

The other was a problem that she couldn’t figure out; the being in front of her was an Upper Demon. Her aura far surpassed any of the Lower Rank Demons, but it was well below Third Rank. 

‘Have I gotten that strong? Or is it a trap?’ It was too tempting a trap to look over, but an image flashed in her mind when she was about to attack. 

If they hadn't been evacuated, the city, the people right now, the casualties would be off the roof, “I’ll hold out as long as I can!” 
“You will release me this instant!!!” The Demon pierced her sashes towards Ai, who slashed them all apart. 

“Say, aren’t you a little weak for being an Upper-Rank Demon?”

“YOUUU!!!!!!!!” 

Outside Prison, 

Maiko and Zenitsu, alongside another of the three wives, and Tanjiro reached them before Tengen did. But Tengen wasn’t far behind; he appeared in front of his two wives, “You two are safe!” 

He wrapped his hands around them, hugging them, and the two felt as if someone had held the sky is falling on them. 

Both smiled warmly, burying their heads in his chest, “Lord Tengu?” 

“Where is Suma?” 

The co-wives became downcast, apologizing, “We don’t know…and Hinatsuru…she has been poisoned…do you have the antidote?” 

Tengen looked towards his wife, Hinatsuru, noticing the signs of a familiar poison, one his wife probably took on purpose and fed her the antidote. 

“Sorry…I am late….” 

“No…you are on time, My Lord.” 

Tengen narrowed his eyes, “How is the evacuation?” 

“It’s done around a few blocks, but we are still clearing more. But I am more worried about that Demon Slayer girl that came with you. She’s trapped inside there with that Demon!” 

Tengen clenched his jaw before letting out a relieved sigh, “She probably did so to stop the collateral damage from happening. Did she say something?” 

Maiko hesitated, looking down, “That it won’t happen…not until she is dead.” 

Tengen’s ear twitched; for more than one, he could hear the vibrations underneath him and the shell in front of him, “Let’s break this first!” 

He slashed the shell, and multiple deep cuts appeared on it, healing the next moment. 

Tengen stood on the other side of the shell in shock, and a grin appeared on his face, “I underestimated that girl!”

He looked over his shoulder, sucking in breath, “Sound Breathing! First Form! Roar!” 

He jumped up, holding his two swords, one in each hand, slamming down the hilt on top of the shell, and a large crater formed below them, but barely any crack appeared on the shell. 

Tengen rose from the blowback, narrowing his eyes as he turned in the air, ‘The shockwave traveled to the ground.’ 

He turned and landed on the side, looking at the ground before looking up at the shell, “First, let’s break this!” 

Hundred of meters under the ground, 

“What is this place, huh?!” Inosuke raised his swords, “I came following that weird Demon! But what is this?! What are they, people? Sashes?! 

“Why have you come to my pantry? You un-clear, dirty pig!!!” 

“A talking worm?!” Inosuke raised his swords, the face hidden inside the boar’s head twisted in pleasure, “Finally! I can fight!” 

While Inosuke started his battle, something had changed about the stalemate above. The shell that had kept the Demon inside started breaking apart. More and more cracks appeared until it crumbled apart, revealing the Demon, standing with her sashes wrapped around Ai’s neck, who couldn’t move at all. 

“Heh, you are a human after all…running out of breath, good for me,” Daki narrowed her eyes, looking at the girl whom she wouldn’t let breathe, but that girl still managed to let out a few words in a hoarse voice. 

“Evacuations…?” 

Tengen slashed apart the sashes, catching her in his hand, appearing away from the Demon before she even reacted, “Everyone is safe, but you. You are just like Rengoku said. Do you seek death?” 

Ai coughed, feeling the painful drawback of Wood Breathing in her body. She knew what she wanted to say, a reply to his question, but before she could tell him, she lost her consciousness, sinking into the darkness.