Time flew by.
In the blink of an eye, an entire month had passed.
During this period, Tetsuya Kamihara stayed at Tamayo’s estate.
Just as they had predicted, Muzan Kibutsuji hadn’t merely sent a single Lower Rank demon to hunt her down.
Countless demons had passed by the manor over the last month, and there was no shortage of Lower Ranks among them.
Fortunately, Tamayo’s illusion Blood Demon Art was incredibly reliable.
It perfectly masked their presence, preventing the vast majority of demons from noticing anything amiss with the house.
As for the few demons that blindly stumbled inside by sheer dumb luck?
Tetsuya casually beat them until their bones shattered, tossed them out into the sunlight the next day, and watched them instantly turn to ash.
There was another reason he had stayed here for a whole month.
Immediately after slaying Kamanue, Tetsuya had returned Kanae Kocho’s soul to her physical body.
However, Kanae never woke up.
She lay on the crisp, white hospital bed with her eyes tightly shut.
Her breathtakingly beautiful face was peaceful and serene, a soft smile resting on her lips.
The only sign of life was the faint, rhythmic sound of her breathing.
There wasn’t the slightest indication that she was going to wake up.
Tamayo walked over.
“It’s exactly as you guessed.
She is likely using sleep as a substitute to replenish her stamina.
Unfortunately, this is my first time encountering a situation like this as well.” A Hashira of the Demon Slayer Corps turning into a demon—such an event had barely happened a handful of times over the last few centuries.
There were essentially no case studies to reference.
Still, drawing on her profound understanding of demonic biology, Tamayo was able to make a few accurate deductions.
Tetsuya furrowed his brow.
Nezuko Kamado had slept for two entire years.
How long was Kanae going to sleep?
He couldn’t stay here forever.
“I have other matters to attend to, so I’ll leave her in your care,” Tetsuya said.
If he delayed any longer, the damned system’s failure penalty would kick in.
He had to infiltrate the Demon Slayer Corps as quickly as possible.
That Immunity Physique was an absolute must-have.
“Mhm.” Tamayo nodded, her tone resolute.
“I won’t let anyone harm her!” Through their interactions over the past month, Tamayo had learned about what the two of them had been through.
She knew they were people she could trust.
Afterward, Tamayo handed Tetsuya two empty syringes.
If he ever encountered another member of the Twelve Kizuki, she needed their blood for her research.
Tetsuya accepted the syringes.
Having an extra trump card was always a good idea.
The human-turning cure and her composite multi-stage poison were the ultimate weapons for dealing with Muzan Kibutsuji.
“See you later!” Tetsuya turned and left.
Tamayo’s manor was outfitted with quite a few hidden mechanisms.
Even just the ones Tetsuya knew about included multiple secret basements and escape tunnels.
She truly lived up to her reputation as a woman who had tenaciously survived Muzan’s relentless pursuit for centuries.
Leaving Kanae in Tamayo’s care was incredibly safe, which had been his primary goal all along.
Reaching the doorway, Tetsuya glanced back, taking one last, deep look at the sleeping Kanae.
The memory of her sweet smile flashed through his mind.
After parting today, who knew when they would see each other again.
But it was precisely because of this that he was even more determined to follow through with his next steps.
“He’s finally gone,” Yushiro muttered, curling his lip.
His peaceful, solitary life with Tamayo-sama had been completely ruined by Tetsuya’s presence.
Gazing at Tetsuya’s retreating back, Tamayo said softly, “Perhaps that boy is the key to defeating That Man.” “No way,” Yushiro scoffed, his eyes widening in disbelief.
“It is just my intuition,” Tamayo replied.
The feeling Tetsuya gave her was eerily similar to the unparalleled genius swordsman from hundreds of years ago.
After leaving Tamayo’s manor, Tetsuya moved swiftly through the night, heading straight for the Butterfly Mansion.
As the Demon Slayer Corps’ primary medical facility, the Butterfly Mansion was heavily concealed.
However, no amount of secrecy could hold up against an inside job orchestrated by Kanae Kocho herself.
Kanae had spilled every single piece of intel about the Butterfly Mansion to Tetsuya without holding anything back.
Soul Manipulation: Imposter!
Having scavenged quite a few souls along the way over the past month, Tetsuya selected the soul of an ordinary teenager from his reserves.
Activating his Blood Demon Art, a crimson glow enveloped him.
His physique shifted and morphed, gradually transforming into the exact appearance of that teenager.
Naturally, he couldn’t just stroll into the Demon Slayer Corps looking like his usual self.
He’d probably be decapitated on the spot.
Checking his reflection in a storefront window along the street, Tetsuya inspected his new look.
His demonic fangs were gone, his slightly pale skin had returned to a healthy human hue, and every single demonic trait had completely vanished.
He looked exactly like an ordinary, run-of-the-mill human.
The Butterfly Mansion.
Ever since everyone believed Kanae Kocho had died, Shinobu Kocho had become the new master of the Butterfly Mansion.
Inside a spacious room, Shinobu was burning the midnight oil.
She was meticulously studying the toxicology records and knowledge left behind by her Demon Slayer predecessors.
Her physical strength was too weak to decapitate a demon, so she had chosen a different path: poisoning them to death.
‘Yasuo…
I am going to kill you!’ A throbbing vein popped on Shinobu’s forehead as she forcefully suppressed her boiling rage.
The sound of that demon’s voice seemed to endlessly echo in her ears.
“Too weak!” “Too weak!” …
Shinobu bit down hard on her lower lip, her eyes bloodshot.
The memory of her sister’s heart being pierced by that demon flashed through her mind, twisting her own heart like a knife.
She absolutely had to avenge her sister.
She would kill that demon, no matter the cost!
Knock!
Knock!
A soft knock at the door broke the silence.
“Come in!” In that split second, Shinobu’s face returned to perfect calmness, slipping on a sweet, gentle smile identical to Kanae’s.
A thirteen-year-old girl with black hair and blue eyes pushed the door open.
“Shinobu-sama, a letter has arrived for you.” Seeing the letter in Aoi Kanzaki’s hand, a flicker of confusion passed through the depths of Shinobu’s eyes.
Who would be sending her a letter?
Shinobu took the envelope.
“Thank you.” She waited until Aoi bowed and exited the room.
Curious, Shinobu sliced the envelope open.
The moment her eyes landed on the very first line, she practically leaped out of her chair.
[Shinobu, it’s me, your sister Kanae…] There was no mistaking this handwriting.
Shinobu knew it anywhere—it was unequivocally penned by Kanae’s own hand.
The letter began with the same warm, affectionate greetings as always.
Before she even realized it, Shinobu’s eyes were brimming with tears, vivid memories of their time together rushing back to her.
And yet, the person who wrote this was already gone!
At the very end of the letter, Kanae had written a recommendation for a young man to join the Butterfly Mansion as a doctor.
Shinobu quickly wiped the tears from her eyes.
Since it was her sister’s personal recommendation, she would have to see exactly what kind of person this guy was.
Joining the Butterfly Mansion wasn’t going to be that easy!
Having received permission, Tetsuya Kamihara stepped into the Butterfly Mansion.
His face remained perfectly impassive, though the overwhelming, dense scent of Wisteria flowers instantly caused a violent wave of discomfort to churn in his stomach.
Demons below the level of the Twelve Kizuki would likely refuse to come anywhere near these plants.
Thankfully, his strength was worlds apart from what it used to be.
Standing in the courtyard was a beautiful young girl.
It was Shinobu Kocho, whom Tetsuya had encountered once before.
Shinobu had a petite, delicate figure.
Her flawless face featured exquisite traits: crystal-clear, pale purple eyes, a small, refined nose, and thin, cherry-like lips.
A beautiful butterfly ornament adorned the back of her hair.
She wore the standard Demon Slayer Corps uniform beneath a haori bearing a butterfly wing pattern.
This was the very same haori Kanae had left behind.
When the fabric billowed out in the wind, it perfectly resembled the wings of a butterfly.
Bathed in the moonlight, the young girl looked exactly like a gracefully dancing butterfly.
Shinobu’s gaze shifted, locking onto Tetsuya.
“So, is it you?
The person my sister recommended.”