As a Grey Knight In Naruto

Chapter 29 – Second Heart

The quiet of the clinic was absolute.

Late into the night, the world beyond its thin walls had fallen silentl no wind through the trees, no carts rattling down the village road, not even the rustle of leaves. Hajime sat alone in the back room, illuminated only by the flickering glow of chakra-thread lanterns and the faint shimmer of liquid within a sealed glass vat beside him.

He wasn't sleeping. He hadn't slept much since the gene-seed awakened.

Sleep had become optional. His body no longer demanded it with the same urgency it once had. Instead, it waited, alert and ready, obeying his will above its instincts. A side effect, perhaps, of the growing psychic potential within him.

Or maybe it was the sheer pressure of purpose.

Because tonight… Hajime was going to create a heart.

Not a metaphor.

Not a diagram.

A real, living, beating secondary heart, modeled after the biomechanical designs of the Adeptus Astartes.

.....

He had already made the preparations.

Scrolls lined the walls, carefully annotated with Tsunade's research. She had once dabbled in regenerative medicine far beyond what most of her peers could comprehend, even skimming the edge of cellular immortality. He'd devoured those scrolls.

He also had knowledge no one in this world could even imagine: the memories of a Grey Knight Apothecary, sacred blueprints encoded into thought. Schematics for transforming flesh into something divine.

But there were no bio-forges here. No auto-cauldrons. No mechanical gene-vats tended by servitors.

He had to do it by hand.

By chakra.

By thought.

By will.

....

Hajime sat cross-legged, bare-chested, his skin lit faintly by the silver-blue glow of chakra focusing at his fingertips. A long, sharp thread of energy extended from his forefinger, a chakra needle, thinner than hair and honed for surgical precision.

He took a deep breath.

And plunged it into his chest.

Pain lanced through his sternum as the needle slipped between muscle and bone. He didn't cry out. Didn't wince. His breath hitched, then steadied, and his eyes focused like a sniper's scope.

The needle found his primary heart.

With careful guidance, he extracted a microscopic thread of living cardiac tissue, healthy, rich with cells genetically attuned to his body.

The thread shimmered with faint red light as he drew it out and lowered it into the nutrient vat beside him, a clear, sterile cylinder filled with a nutrient broth he'd synthesized from Tsunade's alchemical notes.

He had spent two days perfecting the formula. It contained electrolytes, energy-sustaining enzymes, regeneration stimulants, and a specific balance of trace minerals, an environment that could support accelerated tissue growth without destabilization.

It would have to be enough.

...

Now came the real test.

He placed his hands on either side of the vat and began to channel Yang chakra, the chakra of vitality, growth, and the physical world.

Slowly, the tiny cells within the fluid began to divide.

Then multiply.

Dozens. Hundreds. Thousands.

And as they grew, Hajime guided them, not with scalpel or hand, but with psychic will.

He closed his eyes and reached within himself, not for chakra, but for the Warp. For the invisible, formless wellspring of energy that had awakened inside him when the gene-seed had first taken root.

The memories of the Apothecary returned.

He saw the shape of the heart as if burned into his mind, the second circulatory system it supported, the reinforced valves, the pressure regulators, the fail-safe pump chamber. Not just an organic organ, but a redundant life engine meant to sustain an Astartes through worlds of blood and fire.

It had no true analog in human medicine.

But it would soon exist here, in this world.

He extended his psychic focus into the vat.

The fluid rippled. The cells obeyed.

The growing heart twisted gently, its developing tissue firming under the influence of Hajime's shaping thoughts. He wasn't just growing a lump of meat, he was sculpting an idea into matter.

And it was working.

Hours in Silence

Time passed.

Hours melted away like wax.

The candle burned low. The night deepened.

Still he sat there, hands steady, aura glowing faintly like the last ember of a dying star, but his mind, his will, burned like a furnace.

He channeled chakra in pulses, feeding the growth with refined Yang energy.

He shaped the organ with careful psychic pushes, locking in structure, regulating thickness, sculpting the chambers.

At last, when the first rays of dawn touched the rice-paper wall, and a single bird sang distantly from the rooftop, the heart was complete.

Not quite as large as a normal heart.

But powerful.

Coiled with dense muscle.

Ready for implantation.

And utterly his.

....

Hajime barely noticed when soft footsteps approached from the hallway. Shizune's voice came through the wooden door, gentle and just a bit weary.

"Hajime? Sorry to bother you… just letting you know the Chūnin Exams begin tomorrow. Konoha will be flooded with ninja. Maybe there will be dozen shinobi passing here through konoha. Thought you should be careful."

He blinked.

Tomorrow?

He hadn't realized that much time had passed.

The pieces were moving.

He could feel the threads of fate tightening.

Orochimaru would strike.

The Third Hokage would fall.

And Tsunade would be summoned.

Soon, they would travel to Konoha.

Soon, the world would change.

But Hajime?

He would not be walking into that fire unprepared.

....

He stared at the heart, gently pulsing in its vat, glowing faintly from within.

No chakra signature.

No Astartes organs in his body yet, just this one, soon to be added.

But even without it… he could already feel the foundation solidifying.

Not just chakra.

Not just psychic power.

But the fusion of both.

"I won't just inherit power," he whispered. "I'll build it. Piece by piece. Heart by heart."

His fingers brushed the side of the vat with reverence.

This was not the end.

It was only the beginning.

End of Chapter 29 – Second Heart