Time flew by, and in the blink of an eye, a month had passed.
During this period, Kamihara Tetsuya had been staying with Tamayo, and as they had expected, Kibutsuji Muzan had sent more than just one Lower Moon to hunt Tamayo down.
Countless demons, including several Lower Moons, had passed by the house during this time.
Fortunately, Tamayo's illusion was reliable, masking all scent, so most of the demons failed to detect anything unusual about the house.
As for the demons who stumbled in by accident, Kamihara Tetsuya simply broke their bones and tossed them into the sun during the day, where they instantly disintegrated into ash.
There was another reason for staying there for a month.
After slaying Kamanue, Kamihara Tetsuya immediately allowed Kocho Kanae's soul to return to her body.
However, Kocho Kanae never woke up.
Kocho Kanae lay on the pristine white hospital bed, her eyes closed, her exquisite face serene and peaceful, with a faint smile, and only her subtle breathing could be heard.
There was no sign of her waking up.
Tamayo walked over, "It's just as you guessed; she might be using sleep to replenish her strength. Unfortunately, this is the first time I've encountered such a situation."
A Pillar of the Demon Slayer Corps turning into a demon has only happened a few times in hundreds of years, so there are no reference cases.
However, Tamayo, with her deep understanding of demons, could make some accurate judgments.
Kamihara Tetsuya frowned; Kamado Nezuko had slept for two years, but how long would Kocho Kanae need to sleep?
He couldn't stay here indefinitely.
"I have other matters to attend to; I'll entrust her care to you," Kamihara Tetsuya said. If he delayed any longer, the dog-like system's punishment would come. He had to join the Demon Slayer Corps as soon as possible; he absolutely had to obtain that Immune Constitution.
"Understood."
Tamayo nodded, her tone firm, "I won't let anyone harm her!"
Through a month of interaction, Tamayo had learned about their experiences and knew they were trustworthy people.
Then, Tamayo handed two empty syringes to Kamihara Tetsuya, explaining that if he encountered a Twelve Kizuki again, she would need its blood for her research.
Kamihara Tetsuya took the syringes; more trump cards meant more options. The "Human Transformation Drug" and the compound medicine were potent weapons against Kibutsuji Muzan.
"Goodbye!"
Kamihara Tetsuya turned and left.
Tamayo's house had many hidden mechanisms; Kamihara Tetsuya alone knew of several basements and escape routes. She truly was a woman who had stubbornly survived for hundreds of years under Kibutsuji Muzan's pursuit.
Leaving Kocho Kanae with Tamayo was very safe, which was his original intention.
Reaching the door, Kamihara Tetsuya turned back and gazed deeply at the sleeping Kocho Kanae. In his mind, her sweet smile flashed by.
After this parting, he didn't know when they would meet again.
But precisely because of this, he would be even more determined to do what came next.
"He's finally gone."
Yushiro pouted; his and Tamayo-daren's solitary life had been ruined by Kamihara Tetsuya.
Tamayo looked at Kamihara Tetsuya's departing back and said softly, "Perhaps this young man is the key to dealing with that person."
"No way," Yushiro's eyes widened.
"It's just my intuition," Tamayo said.
Kamihara Tetsuya gave her a feeling similar to that genius swordsman from hundreds of years ago.
Leaving Tamayo's residence, Kamihara Tetsuya moved quickly through the night, heading straight for Butterfly Mansion.
Butterfly Mansion, as the Demon Slayer Corps' medical facility, was very secluded, but it couldn't hide from Kocho Kanae, the insider.
Kocho Kanae had told Kamihara Tetsuya everything about Butterfly Mansion without reservation.
Soul Manipulation - Imposter!
Through his scavenging along the way, Kamihara Tetsuya had accumulated many souls, from which he found the soul of a young boy.
Activating his Blood Demon Art, a blood-red light enveloped him, and his figure changed, gradually transforming into the appearance of that young boy.
He naturally couldn't join the Demon Slayer Corps in his original form; he would likely be slain on the spot.
Looking at his reflection in a roadside shop window, Kamihara Tetsuya examined his appearance. The demon fangs were gone, his slightly pale complexion had returned to normal, and all demonic features had completely vanished. He looked like an ordinary human.
Butterfly Mansion.
Since Kocho Kanae was presumed dead, Kochou Shinobu became the new mistress of Butterfly Mansion.
In a spacious room, Kochou Shinobu read by lamplight, diligently studying the toxicology knowledge left behind by the Demon Slayer Corps' predecessors.
Her strength was insufficient to cut off a demon's head, so she chose another path: poisoning demons.
"Yasuo, I will definitely kill you!"
A vein throbbed on Kochou Shinobu's forehead as she suppressed her anger. The demon's voice seemed to echo endlessly in her ears.
"Too weak!"
"Too weak!"
...
Kochou Shinobu bit her lower lip tightly, her eyes red, as she recalled the scene of her elder sister's heart being pierced by a demon, feeling as if her own heart was being twisted.
She had to avenge her sister and kill that demon, no matter the cost!
Thump! Thump!
A faint knocking sound came from the door.
"Please come in!"
In that instant, Kochou Shinobu's face returned to calm, revealing a sweet smile identical to Kanae's.
A thirteen-year-old girl with blue eyes and black hair pushed open the door, "Shinobu-daren, this is your letter."
Seeing the letter in Kanzaki Aoi's hand, a hint of confusion flashed in the depths of Kochou Shinobu's eyes. Who would send her a letter?
Kochou Shinobu took the letter, "Thank you."
After Kanzaki Aoi left the room.
Kochou Shinobu curiously opened the letter, and upon seeing the first sentence, she instantly couldn't sit still.
"Shinobu, I am your older sister, Kanae…"
Kochou Shinobu couldn't mistake this handwriting; it was personally written by her sister, Kocho Kanae.
The letter, as always, expressed warm greetings to her. Unbeknownst to Kochou Shinobu, her eyes were already soaked with tears, and their past interactions flashed vividly in her mind.
However, that person was no longer here!
At the end of the letter was a recommendation for a young man to become a doctor at Butterfly Mansion.
Kochou Shinobu wiped away the tears from the corners of her eyes. Since it was her sister's recommendation, she would see who this person was. Joining Butterfly Mansion wasn't that easy!
After receiving permission, Kamihara Tetsuya entered Butterfly Mansion, his face expressionless, but the strong scent of wisteria made him feel intensely uncomfortable.
Demons below the Twelve Kizuki level probably wouldn't want to get too close to this plant.
Fortunately, his strength was not what it used to be.
In the courtyard stood a beautiful young girl, Kochou Shinobu, whom Kamihara Tetsuya had seen before.
Kochou Shinobu had a petite and delicate figure, with exquisite facial features carved onto her beautiful face. Her light purple eyes were clear and deep, her nose was small and refined, and her small mouth was thin and delicate like cherry blossoms. She wore a butterfly hair ornament at the back of her hair.
She was dressed in the Demon Slayer Corps uniform, with a haori adorned with a butterfly wing pattern over it.
This haori was left behind by Kocho Kanae. When the haori spread out in the air, its shape was very similar to a butterfly. Under the moonlight, the girl looked like a dancing butterfly.
Kochou Shinobu's gaze shifted to Kamihara Tetsuya, "Are you the one my sister recommended?"