As a Grey Knight In Naruto

Chapter 39 – Forge of Muscle

It was late afternoon when Hajime stepped into the back room of the clinic, where Tsunade and Shizune were sorting tinctures and bandage rolls. The paper windows glowed gold in the dying sunlight, casting long shadows across the floor. The scent of herbs and disinfectant lingered in the air, familiar and grounding.

"I'll be gone for three or four days," Hajime said calmly, adjusting the collar of his shirt.

Tsunade didn't look up from her ledger. "Another secret project?"

Shizune glanced at him, brow furrowed. "Is it dangerous?"

He offered a faint smile. "It's necessary."

Tsunade finally raised her eyes. Her gaze lingered, not suspicious, but weighing. Judging.

"You'll come back stronger, I assume?"

"That's the idea," Hajime replied with a respectful nod.

"Then don't die. We need someone competent while I'm drinking," she muttered, waving a hand. "Go."

Tonton oinked quietly at his feet as he turned and stepped out the door, vanishing into the dusk.

That night, Hajime walked deep into the mountains, beyond the reach of any wandering shinobi. He reached his underground chamber, his sanctuary carved into the stone with earth chakra and psychic will. The smooth black walls glowed faintly with stabilizing seals and psychic containment glyphs. The air was clean, recycled through filtration arrays of his own making, kept at optimal oxygen levels. It was a place meant for transformation.

The Biscopea within his chest pulsed gently, a new organ, still young, but already secreting chemical instructions. Testosterone levels had skyrocketed, along with growth hormone analogs, cortisol regulators, and protein-synthesizing signals. Hajime could feel it deep in his muscles. It was like an ember waiting for oxygen.

And he would give it fire.

He extended his hand, fingers glowing with silver-blue psychic light. The earth groaned as it responded to his will.

Massive gym equipment began to form, stone and alloy compressed into dense, seamless plates, rods, and mechanisms. He didn't mimic modern Earth's gyms. These were tools of war, weighted pull-up towers built from granite slabs, squat racks capable of holding literal tons, adjustable gravity platforms with chakra regulators, and kinetic resistance walls reinforced by metal alloys woven with chakra threads.

Then he formed the cuffs, wrist, ankle, and torso weights, made not to be lifted, but endured. Each band bore sealing marks that increased their gravitational pull as he moved. Just lifting his arms would become a strain. And that was the point.

This was no exercise regimen.

It was a ritual.

Hajime stepped into the center of the chamber and removed his shirt. His body, already transformed by the Ossmodula and Biscopea, gleamed under the cool lights of the psychic arrays. His back was cut with sharp definition. His chest had expanded. Veins ran like silver cords across his arms, and his abs were no longer mere definition, they were carved.

But it wasn't enough.

The Biscopea demanded more. It thrived on muscle trauma and recovery.

And Hajime would feed it.

He donned the weighted cuffs and vest, instantly increasing his body's load by hundreds of pounds. Each movement now required chakra efficiency and absolute focus.

He began the regimen.

Deadlifts. Sets of 20. Each pull dragging stone and metal through the floor.

Squats. Weighted beyond natural limits, gravity enhanced by his seals.

Pushups with one arm. Then inverted sit-ups while suspended from the ceiling.

Row pulls with thick chakra-infused ropes wrapped around boulders.

Between sets, he paused only long enough to heal, hands glowing with medical chakra, mending torn muscle fibers at a cellular level, not just restoring, but enhancing. His psychic threads worked inside the tissue, realigning myofibrils, increasing density with each pass.

He ate as he moved, rations of grilled meat, calcium bars, broth infused with fish marrow, and nutrient-dense pills of his own design. All of it metabolized at lightning speed thanks to the Yang chakra swirling within him, hyper-charging his body's absorption rate.

By the second day, his growth had become visible in real time.

As he strained beneath a chakra-infused squat rack, muscles in his thighs and glutes swelled, rebuilt, then swelled again. He could feel the fascia around his muscles stretch to accommodate new mass. Every inch of his body throbbed with regenerative heat.

His breathing never faltered. His heart never spiked. The Warp sustained him, clean, limitless energy that flowed through his nervous system like divine fire. Sleep became optional, not essential. He dozed for an hour at most, psychically aware the entire time.

By the third night, Hajime stood in front of the full-length reflective panel he had forged from polished stone and chakra mirrors.

He didn't recognize himself.

His body was like a war engine, coiled with power, but without excess. His shoulders had broadened, chest expanded further, and even his legs, once wiry, had thickened with dense, athletic muscle. He wasn't bulky, but compressed with strength, like a big cat or an elite assassin.

He clenched his fists and watched the muscle ripple beneath his skin.

The Biscopea pulsed gently in his chest, satisfied, for now.

But something had changed.

As Hajime meditated after his final set, he reached inward with his psychic mind and scanned himself from the inside out. He found something, limits being applied.

The Biscopea, despite its power, was being governed.

By his own biology.

It was holding back, regulating itself to prevent overgrowth or systemic imbalance. Even the psychic enhancements couldn't override the genetic fail-safes.

Hajime understood.

To grow further, to reach true Astartes potential, he needed more.

More organs. More reinforcement. More structural support.

Or…

He would have to wait for his natural body to catch up. Late twenties. Early thirties.

When his hormonal baseline reached its peak naturally.

Until then, he had reached the outer edge of what the Biscopea alone could offer.

He exhaled slowly and sat in silence, heartbeat steady, hands resting on his knees. The gym around him faded into darkness as the chakra lamps dimmed. Only the faint pulse of the Warp remained, humming through his veins like a second circulatory system.

He had grown. Visibly. Functionally. Permanently.

But the road ahead was long.

And the Forge of Flesh was far from finished.

End of Chapter 39 – Forge of Muscle