"This doesn't make any sense," Sakura growled, kneeling by the old man's side and infusing yang chakra into her palms. "I've never even heard of anyone dying from kunai wounds, let alone from falling down a flight of stairs! Didn't you use to be a ninja, Doctor!? This is a bit pathetic!"
Little by little, she could feel his life slipping away, despite redoubling her efforts.
"Come on, it's just a broken neck," Sakura muttered. "I've seen people recover from worse injuries!"
Shinnō's body defied her understanding.
She kept pouring chakra into his neck to locate the problem, but it kept bouncing off or getting absorbed in weird places, making it impossible to determine exactly where his spinal cord had been damaged. Without knowing the precise source of the injury, she could not risk treating him, for fear of making matters worse.
It was almost as if his body were consciously rejecting her efforts, but that didn't make any sense! Was it because he'd cultivated that Body Revival Jutsu thingy that Tenten had mentioned?
"Amaru," murmured Shinnō, blood pooling at the corner of his mouth. "Come closer…"
His neck was twisted at an unnatural angle; almost ninety degrees, by Sakura's reckoning.
"Yes, sensei?" said Amaru tearfully.
"Please don't blame Miss Sakura for what happened to me," he wheezed. "When I jumped in front of you, I had already done so fully knowing I might die… because… because…"
Doctor Shinnō paused for dramatic effect.
"Because…?"
"Because you're the one I recognise… as my disciple," he said weakly. "It's all up to you now… I know you don't like her very much… but you need to team up with Miss Sakura and find the villagers… save them… that's what's truly important…"
Tears streamed down Amaru's face.
"My headband…" said Doctor Shinnō with a rueful laugh. "It's yours, now… I'd hand it to you, but I can't… feel…"
His eyes slowly closed, and he exhaled one last time.
"Sensei…!" Amaru croaked. "Sensei!"
Sakura pressed two fingers to Shinnō's thick, knotted neck and felt for his pulse… and found none. The legendary doctor was dead, and there was nothing more Sakura could do for him. Perhaps if she'd started with Creation Rebirth and sacrificed some of her lifespan for him, he might have lived, but it was too late to do anything for him now.
A tear ran down Sakura's cheek as she discreetly patted him down, searching for the scroll Tenten had mentioned. The doctor had saved Tsunade's life, so the only way she could repay him was by learning his ultimate jutsu and bringing those responsible for his death to justice…
Nonlethally, of course— because that's what the kind old doctor would want, damn it!
…
Apparently, it had always been the good doctor's wish to be buried in the middle of nowhere, so after helping Amaru dig her sensei a grave, she decided to go out looking for the missing villagers on her own. As long as the little doctoress stayed put, she would be safe.
"Oh, just what am I doing," Sakura sighed to herself, as she kept tossing the secret scroll into the air and catching it, again and again. "Stealing a technique scroll from a grieving girl who's just lost her sensei…"
Sakura felt more than a little guilty for what she had done. Tenten had tempted her into stealing some miraculous medical ninjutsu that promised to train her body without any effort, and in her greed and laziness, she had taken what Amaru was rightfully owed.
"Just one teeny, tiny glance," Sakura told herself. "Then I'll find some way to give it back. Discreetly."
Sakura plopped herself down on a rock in the middle of a clearing scattered with ancient ruins and unfurled the scroll.
Using the Area Scanning Jutsu, which specialised in indoor or underground sensing, she had already determined that an enormous structure lay buried beneath the ground not far from the village. She was already right in front of the entrance that led to the underground labyrinth, so all that remained was to go in… once she had finished learning the scroll's contents.
"The Body Revival Jutsu…" Sakura read out loud. "By stimulating the body's muscle cells using the following method, one can repeatedly trigger the muscle fibres' repair cycle."
When muscles are used, tiny rips and tears develop in the fibres. Once these micro-injuries are detected, the body dispatches satellite cells to fuse with the existing fibres and repair them, with the added benefit of adding their size to theirs. Size equals strength, so the more damage accumulates, the stronger the muscles become.
"Using Medical Ninjutsu to train your muscles… this is just like my second favourite anime, Redo of Healer," Sakura mumbled. "Wait no, I meant The Wrong Way to Use Healing Magic…"
Moving right along…
"Myosatellite cells, which are a type of stem cell, can be further stimulated to choose which type of muscles the user wishes to develop…"
Generally speaking, there are two types of muscles.
Due to his Uzumaki genetics, which specialise in staying power, Naruto's muscles are composed almost entirely of slow-twitch red fibres. He is not especially strong or muscular in appearance, but rather lean, as his musculature is geared towards pure endurance.
Tsunade, on the other hand, was born with monstrous strength and thus began life with a physique composed purely of fast-twitch white fibres, which are bulky and tire quickly but deliver explosive power and speed. If she trained her strength even a little, she would become a hulking muscles monster. After three years, Sakura's muscles had completely turned white, due to her having stolen Tsunade's breasts.
"But that's the problem," Sakura muttered to herself. "White muscles provide speed, but if they grow too large, they'll weigh me down and limit my range of motion… not to mention look ugly."
Sakura was worrying too much— she was already thick enough in the right places that no amount of muscles would ever make her look unwomanly.
"But what if I could combine the two types?" Sakura wondered out loud. "Improve on Shinnō-sensei's jutsu?"
Thanks to Lady Tsunade's lessons, Sakura had learned that the vast majority of people, save for the exceptions named above, are born with an even split of red and white muscle fibres, which means they carry the strengths and weaknesses of both types of muscle in equal measure.
However, what if she were to combine the strengths of the two types of muscles, while eliminating the downsides? Keeping the strength and explosive power of white fibres, while obtaining the stamina and low-profile leanness of red fibres? She already had an all-white physique, so if she obtained an all-red physique on top of that… wouldn't she get a brand-new kind of all-pink muscle…?
"Hang on, isn't this part copied directly from Lady Tsunade's Creation Rebirth Jutsu?" Sakura said, frowning, as she further unfurled the scroll. "And this passage on the Eight Inner Gates… aside from obtaining these Kinjutsu directly from their creators, the only way Shinnō-sensei could have learned the training methods is by consulting the Scroll of Secrets! But how on earth did an outsider gain access to that!? Something's not right…"
Fully absorbed in her theorising, Sakura failed to notice the dark shadow slowly rising from the ground behind her…