In the afternoon, sunlight streamed through the wooden windows of the Butterfly Mansion, illuminating its spacious and bright interior.
Amidst the interplay of light and shadow, a faint smell of disinfectant and the lingering fragrance of Wisteria filled the air.
In front of a large, long wooden table, two beautiful figures were looking down, intently staring at the various bottles and jars on the table and the slides under the microscope.
"Miss Tamayo, regarding the latest purification plan for this Wisteria Poison!!"
"... I think adding a little bit of Thunder Knot Grass juice to the third step might speed up the spread of the toxin in the demon's blood!"
Shinobu Kocho held a slender glass test tube in her hand, her purple eyes gleaming.
She wore that form-fitting Demon Slayer Corps uniform, which perfectly accentuated her petite figure.
That delicate, doll-like face possessed a captivating air of meticulousness and seriousness.
"Hmm, this idea is bold, but it's definitely feasible!"
"... The active ingredients in Thunder Knot Grass might be able to break through the drug resistance barrier of high-level demons."
Standing beside her Tamayo, dressed in an elegant, plain-colored kimono.
Unlike her previous cold, pale, and sickly appearance, Tamayo's fair cheeks now had a healthy rosy glow, a trait that belonged to a living person.
She succeeded!!
The Demon Transformation Medicine, the culmination of centuries of effort, has completely eradicated the evil cells from her body.
She now has a warm body temperature again, and a human heart beating vividly in her chest.
"Lord Tamayo! Please have some tea!"
Just then, a figure carrying a tray approached with lightning speed.
Yushiro's eyes were filled with pink heart-shaped bubbles. He moved with extreme gentleness, carefully placing a cup of perfectly warm black tea next to Tamayo.
"Tamayo is now in a precious and delicate human body. Looking at a microscope for too long will damage your beautiful eyes!"
"... Please have some tea to soothe your throat, and then let me massage your shoulders!"
Yushiro's tone was so gentle it could drip honey, and his eyes seemed to wish they were glued to Tamayo.
In order to maintain his power to protect Tamayo in this perilous world, Yushiro resolutely refused to take the precious Demon Transformation Medicine.
In his view, the human body is far too fragile.
It gets sick, it ages, and even a small cut can cause it to bleed profusely.
Now that Lady Tamayo has returned to the sunlight as she wished, it is enough for him to be the executioner who shielded her from all dangers in the darkness.
What does it matter if I'm a demon for life, as long as I can stay by the side of this woman who is as beautiful as a goddess?
"Thank you, Yushiro. I'm not tired."
Tamayo smiled gently, picked up her teacup, and took a sip.
Not far away, Kanae Kocho sat quietly on a bamboo chair, her hands supporting her cheeks, watching them.
She wore a pink and white fitted casual dress, her breathtakingly full curves rising and falling slightly with her breath, exuding a unique and fatal charm of a mature older sister.
Her long, black hair was casually tied back, and a serene smile graced her exquisite face.
However, this wonderful academic atmosphere did not last long.
"Bang--!"
The wooden door was violently kicked open from the outside!
"Damn it! Who taught you to open the door so roughly!"
Yushiro's pink bubble burst instantly.
As a demon, his senses far surpassed those of ordinary people. The moment the door was kicked open, he smelled an extremely violent Demon Aura!
Like an enraged lion protecting its cubs, Yushiro suddenly took a step to the side, using his body to completely shield Tamayo behind him, and pointed at the door while cursing loudly.
"Giyu Tomioka! You rude, expressionless guy!"
"Lady Tamayo is an incredibly delicate human being right now! If the sound of you kicking the door frightens her beautiful heart, I'll definitely twist your head off and use it as a chamber pot!"
"... What disgusting garbage did you bring back?!"
Giyu completely ignored Yushiro's roar.
He walked to an empty medical bed and, like unloading cargo, tossed the figure on his shoulder onto the pristine white sheets.
"This is not garbage."
Giyu patted the dust off his shoulders, his deep blue eyes completely calm, his tone flat and without a trace of emotion.
"This is Tanjiro Kamado."
"Why?"
Kanae paused for a moment, her serene smile fading slightly, and immediately stood up and walked over.
Tanjiro? That gentle boy who sells charcoal?
She looked at the boy on the bed, who exuded an eerie aura, and her beautiful brows furrowed instantly.
"How did he get into this state? Did he encounter a high-level evil spirit...?"
"Wait! This stench is absolutely horrifying!"
Yushiro's nose twitched twice, his eyes instantly shrank to the size of pinpoints, and all the muscles in his body tensed to the extreme.
He pushed Tamayo back even further as if facing a formidable enemy, cold sweat beading on his forehead.
"This guy isn't human! Giyu Tomioka, are you insane?!"
"You actually brought a high-level evil spirit into the Butterfly Mansion?!"
"... His aura was ten times more terrifying than that of the Lower Rank!"
"He truly is a demon now."
Giyu spoke directly, interrupting Kanae's guess and confirming Yushiro's warning.
The moment those words were spoken, the air in the pharmacology lab seemed to freeze for two seconds.
"Mr. Tomioka, that joke isn't funny at all."
Shinobu Kocho put down the test tube in her hand, her brows slightly furrowed.
"Tanjiro is a human, how could he suddenly turn into a demon?"
"I'm not joking. He was Muzan injected with a large amount of Demon King's Blood by Muzan, and has been completely turned into a demon."
Giyu's deep blue eyes quietly swept over the crowd.
"Furthermore, due to his unique physique, he overcame his weakness to sunlight the instant he transformed into a demon."
"Clatter!"
Tamayo dropped the pen she was holding onto the table, as if struck by lightning.
"Overcame... sunlight?!"
Tamayo's voice was trembling.
She had studied Muzan Kibutsuji for centuries and understood what this meant better than anyone else!
This is Muzan's ultimate goal, which he has been searching for for over a thousand years!