Uchiha Bloodline

In Konoha's forty-fifth year, Kyohaku Uchiha turned ten. Time seemed not to have left many of the marks a child should bear upon him. Instead, it had settled into a composure and restraint far beyond his years.

On the surface, he was an ordinary medical ninja intern at Konoha Hospital. Dressed in a slightly oversized white medical uniform and leaning on a crutch, he moved through corridors and wards filled with the scent of disinfectant. He was mainly responsible for the Animal Training and Rehabilitation Class, though he was occasionally transferred to ordinary wards to assist with simple wound cleaning, dressing changes, and basic applications of the Healing Technique. He worked meticulously and steadily. Though he spoke little, his calmness and reliability, so unlike someone his age, gradually made some of the medical staff overlook both his disability and his youth.

However, that was only one side of his life. The other was hidden deep within Konoha Hospital, inside a highly classified laboratory controlled by Orochimaru.

One or two nights each week, or sometimes during the day while on leave, Kyohaku would quietly enter this underground space, lit by cold white lights and filled with precision instruments and the smell of formalin. This was the central site of his "transaction" with Orochimaru.

"Very good... Keep the Sharingan active. Focus your chakra within the eye meridians and feel those unique fluctuations of Yin-natured chakra..." Orochimaru's hoarse voice echoed through the laboratory. Wearing a white research coat, his golden snake-like eyes fixed on the slender sensors connected to Kyohaku's head and the area around his eyes. Complex streams of data continuously flickered across the instrument screens.

Kyohaku sat calmly in a specially made chair. Within his right eye, the single tomoe rotated slowly, casting an eerie red glow. He controlled his chakra as instructed, while rapidly recording and analyzing every command Orochimaru gave, every reading from the instruments, and every subtle sensation that arose when his Sharingan was active.

Orochimaru displayed an almost obsessive fascination with the Uchiha Clan's Kekkei Genkai. Even though Kyohaku had only awakened a One-Tomoe Sharingan so far, to this scientist, it was still a precious window into the secrets of the Sharingan.

"Incredible..." Orochimaru looked at the specific brainwave patterns on the screen, far more active than those of ordinary people, as well as the gathering patterns of Yin-natured chakra. His tongue unconsciously swept across his lips, and his eyes gleamed with the excitement of discovering a treasure. "Just a single tomoe provides such a remarkable increase in chakra perception accuracy and neural response speed... No wonder the Uchiha Clan produces so many geniuses. These eyes truly are a masterpiece of creation..."

His research covered many aspects: the precise physiological changes and alterations to chakra meridians when the Sharingan was activated; the abnormal degree of optic nerve activation; the roots of its resistance and affinity toward Genjutsu; and even attempts to analyze the mysterious energy within ocular power related to the "reflection of the heart."

Kyohaku cooperated with all of it. He allowed Orochimaru to draw small amounts of blood and somatic cell samples; to record charts of chakra flow throughout his body as he activated and deactivated the Sharingan; and even, during certain non-invasive Genjutsu tests, to describe in detail the changes in his sensations.

The process was not without risk. Orochimaru's gaze sometimes became far too fervent, as if he wanted to dissect Kyohaku along with those eyes. Yet Kyohaku always remained absolutely calm and cooperative. At the same time, the forensic examiner's soul deep within him greedily absorbed every scrap of knowledge.

He himself was also full of curiosity about the seed buried within his Uchiha Bloodline—the Sharingan. Where did this power come from? Why did it require intense emotional stimulation? What exactly were the conditions for evolution? Was pain alone enough? And upon what principles were those legendary Mangekyō Sharingan abilities based?

After cooperating with the experiments, he would often pose carefully considered questions to Orochimaru—questions that seemed innocent, yet struck at the heart of the matter.

"Lord Orochimaru, is the evolution of the Sharingan tied only to the intensity of one's emotions? Or does it also require a deeper understanding and control of chakra nature itself?"

"Different members of the Uchiha Clan awaken their eyes at different ages and possess different abilities. Beyond aptitude, could this also be related to the qualities of their own spiritual energy?"

"What is the fundamental difference, at the chakra level, between the 'truth' these eyes see and what ordinary people see?"

These questions sometimes surprised Orochimaru slightly, only for him to reveal an even more interested smile afterward. He appreciated this kind of thoughtful inquiry rather than blind fear or worship. Between the two of them, an odd and subtle relationship gradually formed, somewhere between researcher and test subject, mentor and student.

Kyohaku never took the initiative to inquire into Orochimaru's other research. He focused only on the mysteries of his own bloodline. He knew that the more he knew, the greater the danger, but when it came to the core secret of himself, he had to learn as much as possible.

Over this year of secret research, he gained enormously. Not only did he gain a deeper understanding of the limits and applications of the One-Tomoe Sharingan—enhanced dynamic vision, observation of subtle chakra flow, and basic Genjutsu detection and casting—but through Orochimaru's instruments and data, he also gained a preliminary understanding of the biological and chakra-based foundations behind this Kekkei Genkai.

At the same time, he came to understand more clearly just how terrifying and brilliant Orochimaru was. The breadth of his knowledge, the sharpness of his thinking, and the sophistication of his experimental methods all far exceeded ordinary imagination. Seeking the hide of a tiger was a dangerous undertaking; one had to remain vigilant at all times, but the rewards were equally astonishing.

Whenever he left the cold laboratory and returned to the hospital corridors beneath the sunlight, Kyohaku felt as though he were passing between two entirely different worlds. One was a white world filled with the scent of disinfectant, pursuing healing and life. The other was a gray realm permeated with formalin, exploring the taboos of life and the origins of power.

And Kyohaku Uchiha walked calmly along the edge between them, making use of every available resource, absorbing knowledge, accumulating strength, and gradually uncovering the secrets hidden deep within his bloodline. The red single tomoe that occasionally emerged silently when no one was around also seemed to grow ever deeper through this unceasing exploration.