After tracing the star chakra to its source, Naruto, Sakura, and Sasuke had found the trainees collapsed in a circle beside the canyon filled with poison gas. Since they couldn't just leave them there, Naruto and Sakura had carried them back to their lodgings in the crater near the training building— where they discovered Hokuto keeping watch over her ailing friend, Mizura.
"It's no good," sighed Sakura, having just completed her medical examination of the sickly boy. "I can heal scratches, surface-level wounds— that's sort of thing. But this? Maybe Lady Tsunade could help, but I'm just a trainee medic, I wouldn't even know where to begin."
Mizura had suffered the most from the star training, by far.
His body was so emaciated and gaunt that his ribs protruded sharply beneath his pallid skin. Worse still, the radioactive meteorite had caused glowing tumours to form in his body— tumours that forcibly drew chakra at full strength from nearby healthy cells.
In essence, the energy normally produced through cellular respiration was diverted to generate excess star chakra, which in turn fed the cancerous growths. This left Mizura's healthy cells starved of energy, unable to sustain themselves or carry out their functions, steadily worsening his condition.
"Oh, I see," said Hokuto quietly, before adding hopefully, "then, is Sumaru all right? I didn't see you bring him in yet…"
"I'm sorry," said Sakura softly. "The thief took him away before we arrived."
She couldn't quite put her finger on it, but something about the kidnapping had felt rather… off.
"But I'm sure he'll turn up sooner or later!" added Sakura comfortingly. "Sasuke stayed behind to look for clues."
"Leaving us to do the heavy lifting," grunted Naruto, as he dropped a boy onto a futon. "There, that's the last one."
Sakura checked the unconscious trainees' vitals one by one. While none had deteriorated as severely as Mizura, it was clear that none were as healthy as they should have been. Perhaps there was some unknown factor influencing how resilient their bodies were to radiation exposure?
Ding! Resistance is determined by the concentration of Ōtsutsuki DNA, which is naturally insusceptible to denaturation caused by cosmic rays. Senju, Uzumaki, Hyūga, Uchiha and Kaguya clan members would exhibit resilience to the meteorite's chakra enhancing radiation but not complete immunity.
Since Sakura relied on her chest for around 99% of her powers, the risk of developing breast cancer clearly outweighed any potential gain from manifesting star chakra— especially since she was three times more resistant than the average shinobi, which would make it more difficult for her to mould it. As such, stealing breast chakra from any of the Hidden Star kunoichi was right out.
"Then," said Hokuto hesitantly. "Is it true? Do we all have… tumours, like you said yesterday?"
Sakura nodded.
That was how the star training worked— converting healthy cells that produced normal chakra into cancerous cells that produced 'star' chakra.
The main difference between Mizura and the others was that he was too compatible with the meteorite's radiation— the proliferation of star cells was out of control, so his body was changing far too fast to be able to cope. At this point, Mizura's body had changed so drastically that it was as if he'd completed the star training more than a dozen times in a row, but unfortunately, all of the star chakra he was automatically generating was being directed inwards to corrupt more healthy cells.
"Even if you complete the training, I suspect you'll all still be living on borrowed time," explained Sakura, shaking her head sadly. "It might take dozens of years or more, but it's only a matter of time before you reach Mizura's stage."
A typical star shinobi would learn to control their power step by step until the star training was completed. But ironically, even if Mizura could somehow master star chakra in a day, he had grown so weak that he would be unable to use the incredible power he had gained!
"This is horrible," sniffed Hokuto. "Akahoshi-sama said the training would be difficult and that we might die, but he never said anything about cancer… we just pushed through the pain, because we wanted to make Hoshigakure great again…"
A village that does not care for its shinobi has no future, which is why the Third Hoshikage had banned the star training.
"He didn't tell you?" asked Sakura, startled. "Do the adults know what that training is doing to you?"
In Sakura's opinion, most of the adults probably didn't know, because they were ordinary shinobi who lacked star chakra. If Akahoshi had only included children in his revival of the star training following the Third Hoshikage's death not too long ago, it was probably because he thought they'd be easier to manipulate than adults…
"That bastard," growled Naruto, smacking his fist into his palm. "I'll give him a piece of my mind, y'know!"
"Like it or not, he's our employer," said Sakura morosely. "Our actions reflect on the Hidden Leaf and everyone back home, so as much as I'd like to… ahem. At any rate, our hands are tied. This is a matter of the Hidden Star, so we can't interfere unless they mess with us first."
While hidden villages were partially subsidised by the state they belonged to, they weren't standing armies either, so they couldn't be completely funded by taxpayer money. As such, trust and reputation went a long way for hidden villages, since the bulk of their income would end up coming from mission commissions. After all, who in their right mind would hire shinobi if they couldn't be trusted not to turn on their clients once the job was done?
"Ngh…" groaned Sakura, rubbing her eyes.
It was extremely frustrating to have all this power at her fingertips, but being powerless to use it…
"Are you okay, Sakura-chan?" asked Naruto worriedly.
No wonder so many transmigrators ended up joining the Akatsuki— after living stifling, uneventful lives on Earth, then awakening to chakra and powers that defied logic, only to be shackled by rules and regulations... Of course it was more satisfying to cut loose and live without responsibilities, wasn't it?
"I'm fine," said Sakura tiredly. "I just got some dust in my eyes…"
But she was not some crazed murder hobo who slapped faces all day long and killed needlessly.
While Sakura had done some questionable things to fellow villagers (read: saggy grannies, Yakumo, Tsunade, Anko, Ino), in the past year, she had made meaningful bonds with everyone in the village, and she wouldn't sever them for anything in the world. The Hidden Leaf was her home, and everyone who lived in it was a precious comrade (read: emergency boob supply).
In a way, that was Sakura's Will of Fire!