As a Grey Knight In Naruto

Chapter 30 – The Second Heart

The sun hovered low on the horizon when Hajime finished his last patient for the day, a minor leg fracture wrapped tightly with chakra-infused bandages. The streets of Tanzaku Quarters had begun to thin, lanterns flickering to life along the alleys as merchants closed shop. The clinic, for once, was quiet.

Shizune was busy taking inventory behind the medicine shelves, and Tsunade sat near the window, her posture relaxed, Her Blonde Hair looking very smooth and beautiful, a half-filled cup of sake resting lazily in her hand. She looked peaceful, almost too peaceful for someone who had threatened to throw scalpels at him for asking too many questions days earlier.

Hajime approached with calm steps. She noticed without looking, her golden eyes peeking sideways. "You need something?"

"I'd like to take a few days," he said evenly. "Personal reasons."

Tsunade raised one brow, pausing just long enough to hint at suspicion. "Personal?"

"It won't affect the clinic."

She eyed him for a heartbeat longer, then yawned. "Just don't drop dead in a ditch. You still owe me two weeks of salve-stirring duty."

A herbal

That was all the permission he needed.

By nightfall, Hajime was already on the move. A sealed scroll over his back, his medical tools tightly bound in a kit. No one watched him leave, he made sure of that. The boundary wall of Tanzaku Quarters slipped behind him, and ahead stretched the forest, quiet and windless under the rising moon.

Several kilometers out, in a secluded grove surrounded by dense rock formations and thick soil, he began to shape his sanctum. He closed his eyes, drew chakra into his hands, and reached deeper, with his mind. Earth bent at his will. The ground split and receded. Stone smoothed, walls hardened, and a tunnel opened downward into the darkness.

He entered and sealed the entrance behind him.

A chamber of silence formed, a dome-shaped cavity in the earth, no larger than a small cellar. It was plain, utilitarian, carved with purpose. He extended a wave of psychic energy across the space. It swept through like cleansing fire. Bacteria, spores, germs, every trace of life was erased at the molecular level.

The chamber was sterile. The walls were solid. The floor smooth beneath his bare feet.

This was enough.

He unrolled his tools carefully onto a stone slab. Chakra-threaded wires. Antiseptics. His chakra scalpel. A shallow basin. And floating in a sealed vat, suspended in a nutrient-rich solution of proteins and regenerative enzymes, He learned From the Apothecary Grey Knight Memories... The second heart.

It pulsed faintly, encased in fluid.

Days ago, he had pierced his own chest with a chakra needle and harvested heart cells directly from himself. The process had been slow and exacting. But with precision, psychic control, and Yang chakra funneled into the solution, the tissue had responded. He had shaped it day by day with his will, no machines, no servitors, no biotubes, only chakra, knowledge, and absolute focus.

It was ready.

He stripped off his upper robe and sat against the smooth wall, centering his breath. Then, slowly, his consciousness shifted inward. Psychic power flared subtly. In one precise motion, he shut off the pain receptors in his brain. No hesitation. He no longer needed pain to guide his hands. His senses extended beyond nerve endings now. Psychic perception mapped the tissue and veins of his body like a living diagram.

He activated the chakra scalpel. The hum was soft. Elegant.

Then he cut.

A thin line parted across his chest. Skin, fat, and muscle opened layer by layer under invisible chakra light. Blood welled briefly, but was instantly sealed off by chakra pulses. There was no screaming. No trembling. Only silence and breath.

His sternum remained intact, but beneath it, an open cavity waited.

He reached for the vat with telekinesis. The second heart floated gently out, droplets trailing behind. It hung in the air, pulsing slowly, like an embryonic jewel wrapped in glowing arteries.

Guided by thought alone, he lowered it into the cavity.

It nestled beside his primary heart perfectly. Designed from his own genetic structure, it recognized the host. Blood began to circulate, faint and unsteady.

He focused again.

Chakra threads sparked from his fingertips, like shimmering strings of light, and reached into the exposed flesh. Vein met vein. Artery met artery. With psychic control, he guided the connections. Stabilized the flow. Blood surged. The chamber throbbed with energy.

But something was wrong.

The hearts beat out of sync.

One fast. One slow.

His vision blurred. Pressure surged in his lungs. He dropped to his knees, hand to the floor as the imbalance threatened to spiral.

Then he felt it, deep inside, stirring.

The gene-seed within his chest responded.

A pulse of ancient code, not in language, but in design, rippled through his nervous system. Instructions. Optimization. Alignment.

The new heart shifted.

And suddenly, both hearts beat as one.

A deep, powerful thud echoed through his chest, then another, in rhythm. In sync.

He gasped. His hands trembled.

Then it happened.

Clarity.

His vision sharpened beyond normal. Air filled his lungs and seemed to ignite his thoughts. His body pulsed with oxygen-rich blood. His limbs felt lighter. Stronger. He could feel his stamina recovering like water pouring into a dry well.

Chakra surged into balance, almost tripling in recovery rate. Every breath brought life. Every second brought strength.

His wounds sealed shut under a blend of psychic healing and chakra-driven cell regeneration. He sat there, drenched in sweat, heartbeats pounding in harmonious rhythm.

He smiled faintly.

He had done it.

He had created and implanted an organ that did not exist in this world. No chakra beast, no kekkei genkai, no jutsu, not even the greatest clans had something like this.

He was no longer bound by this world's limits.

And this was only the first step.

With the secondary heart now integrated, Hajime could feel its gifts pouring into him with every passing second.

More oxygen and nutrients rushing to muscles and brain.

Muscles recovering faster. Fatigue evaporating.

A backup life system, if his primary heart failed, he would still live.

Cell regeneration accelerating as blood flowed stronger.

And with the enhanced flow and trauma resistance, his body could survive what would kill any shinobi.

He rose, bare feet pressing against the polished stone floor. Every breath was clean. Every heartbeat resonant.

He touched his chest lightly.

This was no longer just his body.

It was a crucible.

One shaped by chakra and war-born memory.

He had begun to rewrite what it meant to be human in this world.

And now…

He was ready for more.

Behind him, the nutrient vat hissed softly as it cooled.

Above, the faint rustling of wind through forest leaves was the only sound.

And deep within, the gene-seed pulsed quietly, silent, watchful, satisfied.

End of Chapter 30 – The Second Heart