Late at night, in the quiet of the night, Mr. Cheng Mo would return to his small but tidy room.
He sat cross-legged and once again immersed himself in the cultivation of the Heart and Soul Secret Canon, gifted by Kagaya Ubuyashiki.
The tempering of the soul was painful and slow, like meticulously polishing the core of consciousness with the finest sandpaper—a tedious and extremely fatiguing process.
But the effects were significant.
His mental power became more refined, and his perception grew sharper.
After an unknown period, perhaps after a deep meditation, or maybe just a moment when things naturally fell into place... Mr. Cheng Mo suddenly felt a strange stirring from his Eye of Truth.
He instinctively maintained the ability and looked at his palm.
What he saw was not just skin texture and the energy flow of blood within the subcutaneous vessels; on a deeper level... he seemed to "see" an extremely faint but truly existing aura emanating from his palm.
The color of this aura... he couldn't accurately describe it with any known color; it was more like a clear and stable sensation.
With a thought, he quietly got up and pushed open the door.
He first looked in the direction of Himura Ruri's room.
In his Eye of Truth, a faint, warm white aura enveloped the girl.
It was like early spring sunlight, gentle and full of vitality.
But at the edges, there was a touch of worried gray, and while the aura's intensity wasn't strong, it exuded a stubborn resilience.
The next day, under the pretext of discussing data, he glanced at Tamayo.
Lady Tamayo's soul aura was a deep purple, stable and powerful, like a bottomless abyss, revealing a tenacious will forged over hundreds of years.
However, deep within that purple light, there was a barely perceptible, twisted black-red shadow, like shackles, which was probably Muzan's lingering curse.
And at the core of the purple light, there was a faint speck of pure white light, which was likely her obsession with seeking salvation.
Mr. Cheng Mo then looked at Yushiro.
Yushiro's aura was a fiery indigo blue, very intense but extremely unstable.
Like a burning flame, it was filled with obsessive protection and strong exclusionary emotions, with almost no gentle transitions.
In the afternoon, Mr. Cheng Mo briefly visited the streets of Asakusa District under the guise of replenishing supplies.
His Eye of Truth operated at a low level.
The bustling crowd transformed into a collection of various auras in his eyes.
Most people's auras were pale white or light yellow, faint and blurry, fluctuating with their emotions.
A woman intensely bargaining with a vendor had an aura flickering with excited red.
A beggar sitting by the roadside in a daze had an aura that was dim and almost extinguished, a dismal sight.
Several children running and playing had bright, jumping, colorful auras.
He even saw a well-dressed man, smiling as he conversed with others, but his aura was a murky, dark gray, filled with the scent of deception and greed.
The intensity and color of a soul's aura seemed to genuinely reflect its owner's mental state, the strength of their willpower, and even parts of their true nature.
Mr. Cheng Mo stood in the bustling crowd, expressionless, but his heart was surging.
This was not a direct improvement in combat ability, but a more fundamental leap.
He could more intuitively perceive the mental state of living beings, the strength of their willpower, and even their latent traits.
This meant that in future confrontations, he might possess unprecedented insight and countermeasures.
And the study of Himura Senichi's condition gained an extremely crucial observational dimension.
Another layer of the world's truth slowly unfolded before his eyes.
Mr. Cheng Mo returned to the laboratory and once again turned his gaze to the crystal statue in the isolation zone.
The upgraded Eye of Truth operated silently, and the world shed its superficial appearance before him.
It was no longer a simple conflict of red light of energy clash against the white light of will.
He saw that Senichi's soul aura presented a highly unique form.
It was an extremely unique, stable, and complex internal structure, like a dense network woven from countless subtle yet incredibly resilient threads of belief, deeply rooted in the deepest parts of consciousness.
And the corrosive energy of the demon blood was no longer a simple foreign invader; they were like countless ferocious black vines, tightly entwined, even attempting to pierce into that soul network, but they were blocked by the network's own powerful resilience and a constantly generated, faint purifying force, forming an extremely tense and dangerous state of stalemate and entanglement.
What caught Mr. Cheng Mo's attention even more was that from the core of that entangled energy, some extremely faint but incredibly strong fragments of will faintly emerged—
...Ruri...danger...hold on...can't hurt...Sakurako...dojo...
...sorry...These fragments were intermittent, like a candle in the wind, yet they carried a moving steadfastness and tenderness.
This was Himura Senichi's core will, which had not been extinguished even in sleep and mutation.
Immediately after, he re-examined the active demon blood sample from Upper Moon Four, Hantengu.
The sight was even more shocking.
The soul remnants contained within that sample were extremely chaotic, like a spilled palette, filled with viscous fear, cowardice, rage, frenzy... all sorts of extreme negative emotions twisted together, tearing at each other, yet forcibly merged by some stronger, darker will, forming that fragmented and terrifying existence.
This was a world of difference from Senichi's state, where he maintained internal structural stability and clear obsessions even while being eroded.
"What do you see?"
Tamayo's voice sounded nearby; she keenly noticed Mr. Cheng Mo's unusual focus.
"Structure, the structure of will, and the essence of erosion."
Mr. Cheng Mo was concise.
He described what he observed to Tamayo in the most precise language possible.
He omitted the colors of the soul aura, emphasizing only the model of "internal network resilience" versus "external entanglement and erosion," as well as the presence of strong lingering intentions.
Tamayo listened, her eyes gleaming with wonder, her breathing slightly quickening: "The structuralization of will... lingering intentions... So that's it, that's why simple blood component analysis always felt like it was missing something..."
"The key lies in the form and strength of the soul's will. This explains why the individual differences are so huge even when infected by Muzan's blood! Even..."
She suddenly turned, quickly sketching on paper, her voice trembling with excitement: "Mr. Cheng Mo, we need to adjust our direction... We might... we truly might be able to touch the core of reversing demonization, and even find clues to breaking the 'absolute control' curse within Muzan's blood!"
A new, clearer, and more exciting research direction suddenly unfolded before the two of them.