The "Perfect Combat Body Modification Project."
This was Hinami's initiative to further develop her unique "Body Dominance"—a power born from the fusion of the Byakugan and the Shikotsumyaku, allowing her to override the natural biological constraints of the human frame.
Using the kinesiology theories from her previous life, she intended to forge a body capable of withstanding the most grueling high-intensity combat.
In the shinobi world, ninjas generally fall into three categories: Taijutsu, Ninjutsu, and Genjutsu. These categories don't dictate absolute power, only the type of techniques a ninja excels in. Both the Kaguya and Hyūga clans rarely relied on Ninjutsu. Aside from the techniques derived from her Shikotsumyaku, Hinami's repertoire consisted only of the basic Academy Three—making her, in the grand scheme of things, barely a step above Rock Lee.
As for Genjutsu, she was entirely clueless.
But in Taijutsu, Hinami—possessing the bloodlines of both clans—was uniquely gifted.
Taijutsu is the art of utilizing chakra to enhance the physical body, using martial techniques to strike down foes. It is the foundation of all shinobi combat. During its execution, chakra floods the muscle groups like a surge of blood, coordinating with martial movements to unleash explosive force. Simultaneously, this chakra-charged muscle gains incredible durability, offering a powerful defense against blunt-force trauma.
Therefore: The stronger a Taijutsu ninja's physical body is; The more chakra they possess; The more their power increases at a geometric rate.
If she could craft a body specialized entirely for war, she could maximize her Taijutsu potential even while her chakra reserves were still limited.
Back in Kirigakure, she hadn't dared to implement these ideas for fear the Anbu would spot the anomalies. Now that she was out, and Kurio Mari's suspicions had vanished, the dormant project could finally be reactivated.
Of course, perfection does not truly exist. To Hinami, "perfection" was a theoretical balance between various combat needs. She had already begun some modifications back in the village—like the hard bone membrane she had grown over her corneas to protect her precious Byakugan.
If she could grow bone over her eyes, she could grow it anywhere.
She appeared soft and fragile, with skin as delicate as water. In reality, beneath the fatty layer of her skin sat a suit of incredibly dense bone membrane covering her entire body. Her abdomen—the most vulnerable area—was shielded by an interlocking lattice of ribs forming an internal suit of armor.
A normal person encased in such bone would be a vegetable, unable to move a muscle. But the power of a Kekkei Genkai defies logic. Through the influence of chakra, Hinami's internal bone plating could be as rigid as iron one moment and as flexible as silk the next, allowing her to move without hindrance. In fact, the skeletal support allowed her to exert even greater muscular force.
"Hinami, your sleeping bag and tent are all set!"
"Thank you!"
Kamine Karin pitched the tent and carefully helped Hinami inside. Hinami had been silent since dinner, lost in thought. As she lay in her sleeping bag, watching Karin diligently zip up the tent, Hinami felt like a patient in a hospital being tended to by a devoted nurse.
Zip.
The tent was sealed. Outside, the orange glow of the campfire flickered.
Through her Byakugan, Hinami saw Mari setting perimeter traps. Arata was perched on a high branch, sleeping fully clothed to prepare for his watch shift. Karin leaned against a tree near Hinami's tent, resting her eyes, while Sanma sat at the very top of a tree, keeping a sharp lookout.
They were a reassuring team. The mission fee was proving to be a bargain.
Closing her eyes, Hinami returned to the design of her body.
She broke combat down into four attributes she remembered from gaming: Attack, Defense, Speed, and Range. Defense and Range were already handled by the Shikotsumyaku. Attack and Speed were her current priorities.
Drawing on her memories of fighting games and kinesiology, she analyzed "Attack." It comprised power, speed, and weaponry. For Hinami, her bones were the ultimate weapon. That left power—and power was where she had the most room to maneuver.
Most people believe that larger muscles equal more power. This isn't strictly wrong, but it's a shallow understanding. Power is influenced by several key factors:
First: Neural Recruitment. The more muscle fibers a nerve can activate, the more power is produced. Second: Initial Fiber Length. Muscles are like rubber bands; if they are too long or too short at the start of a movement, efficiency drops. Third: Leverage. The angle of pull and the insertion point of the muscle determine whether a joint acts as a power-saving or a power-losing lever. Fourth: Fiber Composition. White fibers provide explosive power, while red fibers provide endurance. Balance is key.
Gurgle...
Hinami began to experiment. Beneath her calm skin, her muscle tissue shifted under the gaze of her Byakugan. Chakra surged from her heart, attaching itself to the fibers in her arm.
Snap! Snap!
The sound of snapping rubber bands echoed in her mind. Under her "Body Dominance," muscle fibers were forcibly lengthened and torn, only to be instantly knitted back together by chakra.
Through her Byakugan, she saw the repaired fibers grow thicker and more resilient. The most terrifying part was her control: she suppressed the growth of the sarcoplasm—the fluid surrounding the fibers. Sarcoplasm provides energy but adds bulk without adding raw strength. Since her energy system was entirely chakra-based, she didn't need the bulk.
By suppressing the fluid, she achieved something monstrous: a muscle fiber of the same thickness as a normal person's, but with several times the power.
She pulled her arm from the sleeping bag, flexing it to test the torque and adjusting the ratio of red to white muscle. Fibers thickened, thinned, stretched, and contracted.
Eventually, Hinami's muscle structure approached her ideal.
In the dim light of the tent, she raised her glowing white arm and studied it with her Byakugan. The limb had swelled slightly, but without the bulky "pump" of a bodybuilder. It looked natural, healthy, and harmonious. Because of the bone membrane and thin fat layer, the shredded fibers beneath didn't show on the surface.
Comparing her modified right arm to her left, the right was noticeably thicker, yet it didn't look "muscular" in the traditional sense. It possessed a heavy, porcelain-like beauty, looking more like an ivory sculpture than a human limb.
She gave it a light flick.
Whoosh!
A sharp gust of wind whistled through the tent, sounding like the strike of a heavy spear.
A bit too heavy, Hinami critiqued.
Her arm felt soft and white to the touch, but the fat content was nearly zero. Beneath the skin was the bone armor, and beneath that were muscles as dense as steel cables, wrapped around arm bones harder than diamonds.
The skin to deceive the enemy. The bone membrane to deflect blades. The muscle to absorb blunt force. The marrow-deep bone to provide the foundation.
Wait... I was trying to buff my attack, but I accidentally maxed out my defense? Is this what they mean by 'the best defense is a good offense'? Hinami joked to herself.
While a high-mass limb increased impact force, it also increased inertia, making it harder to change direction and slowing her initial movement.
If she modified her entire body this way, her agility would plummet. This was an extreme, not perfection.
I can't just stack the thickest armor if it means I'm just a punching bag.
In the quiet of the tent, staring at her two mismatched arms, Hinami fell into a deep silence, searching for the golden ratio between speed, power, and mass.