Yae's (Yaehachi) father had been placed in a secluded area not far from the Demon Slayer Corps' headquarters, where wisteria flowers—repellent to demons—were planted inside and outside the building.
When they saw Yae again, the young girl was wearing a Demon Slayer uniform, a Nichirin Blade hanging at her waist.
"Miss Yuko!"
From a long distance away, Yae spotted the benefactor who had once rescued her father from two Hashira. She ran toward her in excitement.
"Long time no see, Miss Yae."
Yuko smiled lightly and greeted her.
Yae's expression overflowed with emotion. "I've always wanted to thank you properly."
After joining the Demon Slayer Corps, she finally understood just what kind of pressure Yuko had faced when she forcibly saved her father from two Hashira.
Every time she thought about it, her gratitude only deepened.
"Miss Yae comes here every night to keep watch," Shinobu said with a gentle smile as she introduced her. "Because she must take care of her father, the Master ordered someone to teach her a Breathing Style and provided her a Nichirin Blade."
"She is already a member of our Demon Slayer Corps."
Yuko nodded slightly. Allowing a demon to live near Corps grounds was already an immense show of trust—at the very least, safety had to be taken seriously.
Yae also didn't want to trouble others.
Yae scratched her cheek shyly. "Well… my Breathing Style is still halfway there. Saying it out loud kind of embarrasses the Demon Slayer Corps."
Shinobu shook her head. "No, no. Miss Yae is very talented. Reaching this level after only two years is already impressive."
Yuko instinctively used the Transparent World. In her vision, the girl's breathing flow resembled… Wind Breathing.
It was still raw, nowhere near Total Concentration Constant, but joining the Corps was certainly no problem.
She seemed weaker than Tanjiro, but Tanjiro's talent was already near the top of the Corps—second only to prodigies like Tokito Muichiro.
Still…
Yuko had thought Yae would use Flame Breathing. With her outgoing, straightforward personality, she seemed like someone who would get along well with the Flame Hashira.
After a brief exchange, Yae finally noticed the two figures behind Yuko—Tamayo and Yushiro carrying multiple bags.
"These two are…?"
"Doctors," Yuko replied.
Yae froze, then her face lit up with joy. She panicked, "I—I'll open the door right away!"
She and Yuko had exchanged letters frequently. She had been waiting two years for this doctor Yuko spoke of.
Flustered, Yae rushed to the house and opened the door. Shinobu thoughtfully brushed aside the wisteria vines so they could enter.
"Please, go ahead."
"Thank you."
Tamayo's impression of the girl improved even further—she was attentive and gentle.
They stepped into the wisteria-surrounded house. A faint scent of blood lingered within. In the center of the room, a demon was chained with heavy iron restraints.
When the demon sensed them entering, the chains rattled loudly. With gray-white hair and a savage face, Yae's father bared his fangs, looking ready to tear them apart—held back only by the iron restraints that bound him.
"Father…"
Yae's eyes shimmered with tears. She wiped them away and explained,
"He's been like this… and the time he stays sane has gotten shorter and shorter."
At first, he could regain clarity whenever Yae called out to him. But as time passed, those moments became fewer.
Tamayo glanced at the containers nearby, noticing the traces of blood within. She immediately understood.
"Blood alone cannot sustain a demon. When starvation sets in, losing rationality is inevitable."
Yae hurriedly asked, "Then what should we do?"
Tamayo soothed her gently. "Do not worry. I came here precisely to resolve this."
Seeing Tamayo's calm expression, Yae's frantic heart settled.
"Although I cannot guarantee he will return to being a normal human, I can modify him to be like Yushiro and myself—able to maintain rationality by consuming only a small amount of blood."
Shinobu's expression shifted subtly. Indeed…
The demons she had encountered all carried a foul, rotten stench, yet she sensed none of it from Tamayo.
In fact, Tamayo's presence felt strangely familiar—almost comforting.
Yae's voice trembled with hope. "You can…?"
Tamayo nodded lightly. "I believe this elderly man possesses a special constitution. It may succeed."
Transforming a demon into one like Tamayo or Yushiro was extremely difficult. In hundreds of years, only the two of them had succeeded.
But this old man seemed different… perhaps there was a chance.
Tamayo surveyed the room. "This place cannot serve as an operating room. Miss Shinobu, could you prepare a larger room?"
"Of course. My Butterfly Estate is nearby—we can go there," Shinobu said immediately.
"Then we'll trouble you."
After thanking her, Tamayo turned to Yuko. "I'll leave the task of restraining him to you."
"No problem."
Yuko flexed an arm confidently.
Yuko stepped before the old man.
He snarled like a beast, snarling and growling as if waiting for a chance to strike.
Yae stepped forward. "I'll help—"
"No need."
Yuko rolled up her sleeves and struck him sharply at the back of the neck.
His vicious face froze. His pupils rolled back, and his body collapsed limply to the floor.
Yae stared wide-eyed, speechless. This was the first time she learned that demons… could actually be knocked unconscious.
Yuko turned to Tamayo. "This works, right?"
"..."
With Yuko assisting, restraining him was easier than using anesthetics.
The group made their way to Butterfly Estate.
"Miss Shinobu, you've returned."
A black-haired, blue-eyed girl in twin ponytails opened the door for them.
Knowing this wasn't the time for introductions, Shinobu instructed,
"Aoi, please prepare an operating room."
"Understood."
Kanzaki Aoi bowed and rushed off to work.
"Please follow me," Shinobu said, leading them.
They brought the old man into the operating room, filled with an array of advanced medical instruments.
In this era, just having this equipment was already a tremendous expenditure.
The Ubuyashiki family's uncanny intuition had allowed them to amass great wealth—perhaps heaven's small blessing granted to aid them in slaying Muzan.
Tamayo looked around and nodded with satisfaction. "Everything is well prepared. Miss Shinobu, you've been very thoughtful."
"It's nothing…"
Noticing Shinobu seemed hesitant, Yuko asked, "Is something wrong, Shinobu?"
Shinobu pursed her lips. "There is something I wish to ask of Lady Tamayo."
Tamayo smiled faintly. "Miss Shinobu, please speak openly."
Shinobu took a small breath. "During the surgery… may I observe from the side?"
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Currently at chapter 393 for advance chapters
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