The carriage stopped at the edge of the Asakusa District in Tokyo Prefecture.
The 'Kakushi' member driving the carriage bowed respectfully to Mr. Cheng Mo one last time, then drove away with the carriage.
Cheng Mo, Himura Ruri, and the large, heavily wrapped box, more than half a person's height, were left behind.
The roar of noise hit them like a physical force.
The clanging bells of the streetcars, the shouts of the rickshaw pullers, the blaring horns of shops soliciting customers, and the noisy chatter of the jostling pedestrians... all intertwined into a kaleidoscopic scene of prosperity that Himura Ruri had never imagined.
She stood rooted to the spot, her eyes involuntarily widening.
The streets were bustling with black cars and ornate carriages.
The shop windows along the road displayed a dazzling array of goods, and in the distance stood towering brick buildings and utility poles.
The pedestrians wore fashionable Western clothes and kimonos... All of this was an overwhelming impact for a young girl who had grown up in a small mountain town.
She felt as if her eyes and ears weren't enough, and her heart pounded in her chest.
There was both novelty and a hint of trepidation at being in an unfamiliar environment.
But she pressed her lips together tightly, not exclaiming or asking any questions like Tanjirou had initially.
She just quietly leaned closer to Cheng Mo, her small hand unconsciously gripping the corner of his clothes.
The young girl tried to make herself look less out of place, suppressing all her curiosity and wonder deep inside.
Cheng Mo paid no attention to the surrounding clamor; his gaze swept around, confirming his bearings.
Then, he did something that almost made Himura Ruri scream.
He very naturally hoisted the impossibly heavy box, containing the crystallized Himura Senichi, securely onto his back with a special harness.
The box was almost a head taller than him, making it extremely conspicuous.
"Mr. Cheng Mo!"
Himura Ruri's face instantly flushed red, her voice filled with urgency and embarrassment.
"Th-this won't do! Let me help carry it, or... or we can hire someone..."
She looked at Mr. Cheng Mo's tall but not burly figure carrying such a behemoth, while she herself stood empty-handed, feeling incredibly ashamed.
Although she was small and had just recovered from a serious illness, she couldn't bear to let her benefactor do such strenuous labor.
Passersby also cast curious and surprised glances, pointing and whispering about the strange duo.
A well-dressed, stern-looking young man carrying a box almost half his height through the busiest street in Asakusa drew many stares from onlookers.
Cheng Mo turned his head to look at Himura Ruri; the girl's face was so red it looked like it might drip blood, and her head was bowed low.
His tone was calm: "It's fine, let's go."
His pace did not slow, and Himura Ruri could only hurry to keep up, trying to ignore the gazes from around them.
Cheng Mo seemed quite familiar with Asakusa; he navigated through the complex, labyrinthine streets, finally turning into a relatively quiet back alley and stopping in front of an old bookstore named "Qing You Hall."
The storefront was ancient and inconspicuous.
He knocked on the door with a special rhythm.
Moments later, the door creaked open a crack, revealing Yushiro's handsome but wary face.
Seeing that it was Cheng Mo, the wariness in his eyes lessened slightly, but when he saw the exaggerated box on his back and the unfamiliar young girl accompanying him, his brows furrowed again.
"Come in," Yushiro's voice was stiff, and he stepped aside to allow passage.
Cheng Mo walked into the shop with the box on his back, and Himura Ruri nervously followed him in.
The bookstore was dimly lit, filled with the scent of old paper and ink.
Yushiro quickly closed the door, cutting off the outside noise.
Through a hidden trapdoor, they descended a staircase into a secret laboratory underground, a place starkly different from the quaint style above ground, filled with medical equipment and glassware.
Tamayo was still wearing her elegant kimono, standing at a lab bench, recording something.
Hearing the commotion, she looked up, and upon seeing Cheng Mo, a flicker of imperceptible anticipation and urgency crossed her eyes.
But when her gaze fell upon the large box on Cheng Mo's back and the nervous young girl beside him, a hint of confusion appeared on her elegant face.
"Mr. Cheng Mo, you've arrived," Tamayo's voice was gentle and pleasant, "And this is?"
"Himura Ruri, she is his daughter and an important eyewitness."
Cheng Mo introduced her succinctly, while carefully unburdening himself of the box from his back and placing it in the open space in the center of the laboratory.
The thick cloth was lifted, revealing the seated, dark red crystal samurai statue.
"This is..."
Tamayo's gaze was instantly drawn to it.
She took a few steps closer, examining it carefully, her eyes filled with the ardent glow unique to a researcher.
"What a peculiar energy state... solidified, contained, yet constantly and slowly strengthening... Is this the special existence you mentioned in your previous letter?"
Yushiro also came closer, his face filled with shock: "This is a Demon? How could it become like this? I've never seen anything like it..."
"This is Himura Senichi; this is his state after his bloodline mutated from refusing to eat humans," Cheng Mo said calmly, then retrieved the special container from his personal space, in which the slightly wriggling flesh of Hantengu was immersed.
"This is the active tissue of Upper Moon Four, Hantengu."
"Upper Moon Four?!"
Yushiro gasped in alarm, his pupils constricting, and an expression of near horror once again appeared on his face.
Even the usually calm Tamayo's breathing noticeably quickened.
She looked at the flesh radiating a terrifying aura in the container, then at the crystal statue, and an uncontrollable, intensely excited research desire erupted in her eyes.
"Mr. Cheng Mo... you truly... always bring incredible surprises..."
Tamayo's voice even had a hint of a tremor; she was almost impatiently eager to begin studying these two incredibly valuable samples immediately.
Ruri, on the other hand, had been in a state of heightened tension ever since entering this hidden underground room.
Tamayo before her was beautiful and elegant, and Yushiro, though ill-tempered, seemed only a boy, but... her keen intuition, or perhaps the instinctive fear of non-human species that humans possess, made her vaguely feel that these two "people" were different from normal humans.
They carried an aura similar to her father's, yet even deeper and colder... "Demon..."
The word flashed through her mind, making her involuntarily shiver.
She immediately lowered her head, not daring to look again, her heart pounding.
She realized that she seemed to have stumbled upon a secret domain of Mr. Cheng Mo's, unknown to others.
He had bypassed Kochou Shinobu and the entire Demon Slayer Corps, coming directly to these two... clearly not wanting the Demon Slayer Corps to know about all this.
This realization made her even more uneasy, yet also made her even more afraid to ask a single question.
She just instinctively shrunk back further behind Cheng Mo.
Meanwhile, far away at the newly established Butterfly Mansion base, Kochou Shinobu had just finished the heavy task of settling the wounded and inventorying supplies.
Kanzaki Aoi was reporting to her: "...The condition of the seriously wounded is mostly stable, thanks to the medicine and treatment protocols Mr. Cheng Mo left behind earlier, it's just..."
Kanzaki Aoi hesitated for a moment.
"It's just that after Mr. Cheng Mo left with Himura Ruri and her father, there has been no news back."
Kochou Shinobu wore her habitual gentle smile, but a flicker of imperceptible doubt flashed in the depths of her purple eyes.
"I understand, you go on with your work."
"Yes."
Watching Kanzaki Aoi's retreating back, she picked up her teacup, took a light sip, and gazed out the window.
Just now, the news conveyed by the Kasugai Crow, that Cheng Mo's final destination was the Asakusa District of Tokyo Prefecture, made the smile on her face stiffen slightly.
Tokyo Prefecture, Asakusa... combined with the secret information within the Demon Slayer Corps, known to very few, about a mysterious "Demon doctor" Tamayo... combined with the Upper Moon sample and the special Himura Senichi that Cheng Mo took... Kochou Shinobu's smile gradually faded, and a complex, unreadable emotion flashed in her purple eyes.
It was not anger, but more like a sense of exclusion and a faint bewilderment.
She murmured softly to herself, her voice so low that almost only she could hear it: "Teacher Cheng Mo... Is this, a lack of trust in me? Or does he think... my abilities are insufficient to participate in such core research?"
Outside the window, the sun was bright, yet it seemed unable to completely dispel the hint of gloom that quietly arose in her heart.