Uchiha Indra returned to Uzumaki Island, victorious after subjugating mist village.
A massive mansion was built for him. Despite multiple partnerships with powerful kunoichi, no woman conceived. The Uzumaki whispered.
Women wondered. But Indra said nothing.
Privately, he retreated into the innermost chamber of his fortress — a place no one could enter without his seal.
What he refined in secret was beyond even ancient Uzumaki methods: a hidden internal chakra mastery that bent biology and battle readiness into a single logic-defying domain.
He called it Dual Cultivation.
🌙 Present Time – Sealed Chamber Beneath the Mansion
Indra sat alone on obsidian flooring. Crimson chakra glowed low, pulled in tightly beneath his skin.
He had not moved for hours. Every muscle fiber in his body obeyed quiet, imperceptible pressure rhythms. Not for strength. Not for meditation.
But for control.
He blinked once.
"They ask no questions. Good."
"Because I won't explain something only I was born to master."
In truth, he had no intention of explaining it.
The technique – the method – the golden finger he made himself by accident... lay buried deep in him.
Not a jutsu. Not fuinjutsu or bloodline.
It was a transformation forged through pain, rage… and discovery.
A method he alone could shape.
Dual Cultivation, he had named it. And it began when he was just nineteen.
🔙 Flashback — The Awakening
That year marked the peak of his instability.
His own chakra was volatile — rich, immense, energized — but unfocused.
His mind control technique of yamanka clan was somewhat odd, it was little bit felt different technique,
At night, it surged through him aimlessly, burned muscle for no gain, flooded his senses with restlessness.
alone in a stone-clad training vault, his calm fractured.
Rage consumed him.
His chakra exploded unstoppably in his limbs, lungs, spine.
His breath grew wild — sharp enough to feel like violence. His body was filled with endless hunger and intense heat and absorption from his main reproductive organ.
His maid, a silent companion sworn to serve the clan line, entered the rupture calmly.
She saw the shattered floor. The heat. The loss of control.
She approached him carefully but she grabbed by indra and she was shocked, she felt hot lower side of her body, whenher body embrace young master.
Her chakra and something was absorbing in indra body from his organ, she was sucked dry, exhausted.
She never asked for permission.
She didn't cry.
And for some reason… her calm diffused the fire.
He had stilled.
🌌 The Realization
As he caught his breath, flat on his back, he looked toward her — exhausted, calm, drained but unharmed.
"That moment... it shifted something."
He felt warmth still pulsing inside, not from rage, but from internal movement.
An unfamiliar rhythm throbbed near his lower abdomen—perfectly defined. He could sense two flow energy refining in his body.
He looked inward.
Not chakra nodes. Not tenketsu points.
"Those were his shame, four balls"
His body didn't match medical scrolls. It never had. His body has born with four ball.
After this incident,
He did experiment and found Two pair of ball — Pair One — were heavy with life-force. Contained pure Uchiha lineage. Reproductive. Primed to imprint bloodline into an heir.
Pair Two?
Different. Still full of fluid—yet emptier. Lacking in DNA, but dense with energy-storing proteins.
"Useless for creating life..."
"But perfect for fueling war."
And how he confirmed it, you can imagine a young man when do self harm battle in heat.
One pair for the clan's future.
One pair for battle endurance, recovery, and internal chakra recycling.
As time passed, he find out that his muscles and body were becoming stronger and enhanced at whole another level, whenever he would meet women with high chakra, his body would transform at another level.
And now… he could feel the valves between them. Normally autonomous. Invisible. But not anymore.
With discipline, he could isolate each channel using chakra pulses along his pelvic floor and nerve network.
"From that moment on, I trained the switch."
"Reproductive mode. Combat mode. Complete separation… perfect control."
He'd never told the maid. Or anyone else.
No one would've understood anyway.
🔄 The Flow Reversal
But that was only the beginning.
Most shinobi expel chakra outward in battle, in intimacy, in pain.
But one night, while syncing his muscle control during bio-feedback meditation, he shifted the flow direction by accident.
The chakra was drawn inward instead of expelled.
It was silent. Natural. Clean.
He began testing rhis techniques using pressure gradients and smooth muscle contraction.
Combining chakra nerve control, breathing sequences, and internal energy mapping...
He developed:
Reverse urethral pull through rhythmic pelvic contraction.
The result?
Chakra-infused life-force — drawn into him through intimacy moment.
No ninjutsu needed.
Just pure precise muscle control and refining that energy in his body like chakra.
"It's not intimacy."
"It's exchange. Measurable. Pure."
The energy he drew pooled in his lower center, then moved into his core meridians.
From there, it could be converted to stamina.
To chakra.
To healing fuel.
Indra stood now, his body pulsing slightly with internal rhythm.
🌙 The Present — Demon Back Relaxed, Mind Sharp
He ran one palm down his arm slowly. Smooth muscle fibers under the skin shifted — chakra moving through every layer naturally.
No fire visible.
But inside? Pressure danced at perfect tempo.
"It only works for me. I don't need to show or told anyone this"
He walked toward the sealed inner sauna chamber, shadows stretching under the flicker of red flame-light.
"I don't need children yet. I'm still crafting the vessel."
He disappeared into the steam, body calm, energy coiled but silent