In the laboratory.
Lady Tamayo frowned slightly, gazing at the sample on the slide below.
Cheng Mo pushed open the inner room door.
"You're back, Mr. Cheng Mo."
Tamayo greeted Cheng Mo when she saw him.
"Look here..."
She moved aside a little, her voice trembling slightly.
"Even when diluted to this extent, the activity and division rate of demon blood cells far exceed normal limits. They are almost... predatorily devouring all surrounding nutrients and releasing an unknown substance, attempting to assimilate normal cells they come into contact with..."
Cheng Mo leaned over to look.
In the microscope's field of view, the diluted demon blood cells were like raging miniature aliens, wriggling and proliferating madly, displaying astonishing aggression.
But this was only the surface.
A faint golden glow silently swirled in his eyes.
The Eye of Truth's ability was deeply activated, and his vision instantly penetrated the microscopic level of matter, reaching something deeper.
What he saw was no longer cellular structures, but the flow and composition of energy.
Deep within the violent demon blood life energy, he clearly "saw" something unique.
It was not pure energy, but rather an extremely subtle yet complexly structured imprint.
They were like the tiniest parasites; no matter how Cheng Mo and Tamayo diluted the density of the demon blood, they remained tightly intertwined, even embedded, within the life energy itself.
"It's not just activity..."
Cheng Mo straightened up, his tone solemn.
"I see an imprint; it's integrated into the life energy, carrying... a fragment of an instructive will."
Tamayo quickly walked to another instrument and swiftly changed the sample.
"Please look at Himura Senichi's blood sample."
Cheng Mo looked again.
The scene was completely different.
That strange "imprint" also existed in Himura Senichi's blood.
But their light was noticeably dim, and their activity greatly reduced, as if they were stuck in quicksand.
A warm, resilient faint golden energy formed a fine net, stubbornly restraining the erosion of those imprints.
Both sides were locked in a difficult tug-of-war.
"And this, the Upper Moon Four's sample."
Tamayo's voice carried a hint of imperceptible excitement.
Hantengu's blood sample appeared under the Eye of Truth; the sight was terrifying.
The "imprints" within were not only vast in number but also extremely active.
They twisted and roared madly, emitting chaotic emotional colors... furious crimson, hateful pitch black, sorrowful gray-blue, hollow pale white... they tore at each other, yet were forcibly blended together by some higher power, forming that fractured yet powerful energy source.
"Indeed... it is as I suspected!"
Tamayo clutched her hands excitedly. She looked at Cheng Mo, her voice urgent:
"I've researched for hundreds of years and have long suspected that Muzan's blood is by no means a simple mutated toxin. It's more like a curse, a contractual carrier deeply rooted in the soul and bloodline!"
Her voice carried a hint of excitement: "That's it, that feeling... it's like an external, malicious core is entrenched deep in the soul, controlling my power and twisting my will!"
"A very apt metaphor," Cheng Mo's voice was steady.
He gestured towards the structures that had nowhere to hide under the Eye of Truth: "Muzan combines his vast life energy, fragmented soul pieces he stripped off, and the most core element... the curse containing absolute obedience and twisted desires."
"The three are blended together, and through the contamination of human cells, they collectively form 'demons,' a highly activated supernatural existence."
Cheng Mo continued: "And the fear of sunlight... is not because the energy itself is fragile, but because Muzan's own soul has a huge flaw."
"His heart is extremely dark, with a fear of death that surpasses everything. Under the interference of this soul-level flaw, the energy framework constructed from his soul fragments has an inherent, self-irreparable structural weakness, which will be completely disintegrated by certain specific spectrums of energy in sunlight."
Tamayo slowly straightened her body, the shock on her face gradually fading, replaced by an unprecedented clarity and sharpness.
Hundreds of years of fog had been dispelled, and the enemy's most fundamental secret was exposed before them.
"Then, to reverse demonization, one only needs to clear out these soul fragments and then perform a blood transfusion..."
She said softly, her gaze burning as she looked at Cheng Mo.
"And to completely kill Muzan is to fundamentally... destroy the soul core that carries all of this."
"As long as he dies, all demons born from him will perish!"
After speaking, the two began the next phase of experiments and discussions.
Himura Ruri sat quietly on a small stool in the corner, several data record books needing to be organized spread out before her.
However, her gaze would occasionally and stealthily lift, falling upon Yushiro, who was always so harsh towards her.
She saw that whenever Lady Tamayo was fully focused on the microscope or writing, Yushiro would stop everything he was doing and just gaze at her.
That wasn't the look one gives a collaborator or a master; it was something... she had only felt in her father's eyes when he looked at her mother, back when her mother was still alive.
Focused, gentle, as if the whole world contained only that one person.
Full of unspoken protection and devotion.
And when Mr. Cheng Mo and Lady Tamayo drew close to discuss, or even became slightly excited due to a breakthrough in an experiment, Yushiro's gaze would instantly sharpen.
He was like a protective young beast, staring intently at Cheng Mo, radiating undisguised vigilance and displeasure, as if any presence approaching Tamayo harbored ill intentions.
A brief break arrived. Tamayo went into the inner room to consult ancient texts, while Cheng Mo closed his eyes in contemplation, seemingly practicing some cultivation method.
Only Ruri and Yushiro, who was cleaning glassware, remained in the laboratory.
The sound of flowing water trickled.
Himura Ruri looked at Yushiro's tense profile and still-furrowed brow, her heart pounding.
She mustered the greatest courage of her life and spoke, her voice as faint as a mosquito's buzz:
"You... must really want Lady Tamayo... to be completely free, right?"
Clang!
The beaker in Yushiro's hand almost slipped.
He spun his head around abruptly, growling in a harsh, nasty tone: "What business is it of yours! Stop making presumptuous guesses!"
His gaze cut through Ruri like a knife, carrying the anger of having his thoughts exposed.
Himura Ruri flinched, shrinking her neck, but she didn't immediately lower her head as usual.
She watched Yushiro, who, though fierce, didn't immediately walk away.
The young girl was silent for a moment, then continued softly, her voice still very small, but with a hint of seriousness: "Me too... I just want my father to come back, to be his old self again, so... Mr. Cheng Mo, he is an important benefactor to us."
She deliberately emphasized the words "us" and "benefactor," then lifted her eyes, bravely looking at Yushiro's gaze, which had become somewhat complex.
"For Lady Tamayo... it's the same. Mr. Cheng Mo might be the only hope."
Yushiro's lips moved, as if he habitually wanted to retort with a few sarcastic remarks.
But the words caught in his throat and he couldn't speak them.
He knew better than anyone that what this weak human girl said was the truth.
Without the theories Cheng Mo brought, those precious samples, and that pair of eyes that could see through to the essence, Lady Tamayo's research might have groped in the dark for much longer.
He glared fiercely at Ruri, finally just turning his head and vigorously wiping the already spotless laboratory bench, his ears, however, were faintly flushed.
From then on, the atmosphere in the laboratory underwent a subtle, indescribable change.
Yushiro still didn't show a good face, and his words were still sharp and harsh.
But he seemed to tacitly allow Ruri to always stay quietly in the corner.
He even saw Ruri rubbing her wrist, tired from organizing data, and with extreme impatience, almost slamming a cup of water down by her hand, then immediately walking away as if nothing had happened.
Himura Ruri looked at the cup of water, paused for a moment, then carefully picked it up.