Hikari's goal was simple: refine her body into a weapon.
By merging the Byakugan's perception with the Shikotsumyaku's bone manipulation, she'd unlocked an ability she called "Absolute Physique Control"—a power that defied human biological limits. Now, armed with fragmented knowledge from her past life (and a lot of trial-and-error), she aimed to forge a vessel worthy of battle.
In the shinobi world, combat styles fell into three categories:
1. Taijutsu (Physical Combat)
2. Ninjutsu (Chakra Techniques)
3. Genjutsu (Illusions)
The Kaguya and Hyūga clans rarely relied on ninjutsu. Hikari's own arsenal was pitiful—basic Academy techniques and her bone-based kekkei genkai. Even in Naruto's world, only Rock Lee had a worse ninjutsu portfolio.
But taijutsu?
That was where her bloodlines shined.
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Taijutsu relied on chakra-enhanced muscles—flooding tissue with energy to amplify strength, speed, and durability. The more chakra and muscle mass a shinobi had, the greater their power.
Hikari's plan? Optimize both.
In Kirigakure, she'd hesitated—too many eyes, too much risk. But now, free under Ritsuki Mari's trust, her experiments could begin.
Her first innovation: subdermal bone armor.
Already, her eyeballs were shielded by a stone-like bone film (which had fooled the ANBU). That same membrane now coated her entire body—beneath a deceptively soft layer of fat, her skin hid interlocking skeletal plates. Her abdomen? Reinforced with crossed ribs.
For a normal human, this would mean paralysis. But the Shikotsumyaku laughed at biology. Her bones could be steel-hard or paper-flexible at will.
And that was just the foundation.
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Hikari's "perfect" body needed four traits:
1. Attack Power
2. Defense
3. Speed
4. Range
Bones handled defense (armor) and range (extendable weapons). That left attack and speed—specifically, muscle efficiency.
Most assumed bigger muscles = stronger hits. A naive view. True strength depended on:
- Muscle Fiber Density (More contractile fibers, less inert "filler" tissue)
- Optimal Fiber Length (Like a rubber band—too loose or taut weakens force)
- Leverage Angles (Physics mattered; a poorly placed tendon wasted energy)
- Fiber-Type Ratio (Fast-twitch "white fibers" for power vs. slow-twitch "red fibers" for endurance)
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Lying in her tent, Hikari rewrote her flesh.
Chakra surged from her heart, saturating her right arm's muscles. Under the Byakugan's precision, fibers snapped, lengthened, and reknit—thicker, tougher. She suppressed useless "filler" tissue, forcing pure, chakra-fed contractile power.
Snap. Crack. Hiss.
Her arm bulged subtly, its weight tripling. Yet outwardly? Still a girl's slender limb—pale, unmarred, deceptively delicate.
She flexed.
Whoosh—
The air rippled. A single motion sent gusts tearing through the tent.
Result:
- Outer Layer: Soft skin (disguise)
- Middle: Bone armor (slash resistance)
- Inner Muscle: Ultra-dense fibers (blunt-force cushioning)
- Core: Titanium-grade bones (structural integrity)
…Wait.
She'd aimed for offense but accidentally maxed out defense. Typical.
Now, her right arm could punch through stone yet weighed like a boulder. Mobility would suffer if she scaled this up.
Time to recalibrate.
Comparing her asymmetrical arms, Hikari pondered:
"The golden ratio… Where's the balance between speed, power, and mass?"
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Outside, her team kept watch:
- Mari (setting perimeter traps)
- Shin (napping in a tree for night shift)
- Karin (leaning against Hikari's tent, half-asleep)
- Yōma (perched high, scanning for threats)
"Worth every ryō," Hikari mused, grateful for their vigilance.
As the firelight flickered, she resumed her work—sculpting herself into something beyond human.
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