After the experiment was over, Shinji and Yakumo left the laboratory together and headed for the Ninja Academy.
"I never expected the flesh and blood of those monsters to contain such terrifying power. Even the most potent poisons we've collected can't completely destroy their cells."
As they walked, Yakumo couldn't help sighing.
For the past few days, Tsunade's experiments had focused on countering demons' ability to regenerate their flesh.
After all, although the Upper Ranks had been defeated in the war in Grass Country, the whereabouts of the high-ranking Upper Ranks—Upper Moon One, Upper Moon Two, and Upper Moon Three—as well as that terrifyingly powerful mysterious man were unknown. None had been confirmed dead, so the village had to prepare for the possibility that the Upper Ranks might return.
That was why finding a way to counter the demons' regeneration had become the top priority for the research team led by Tsunade.
"Yeah!"
Shinji sighed softly, too.
To be honest, even he had been shocked by the demons' regenerative abilities when he saw the data for himself.
Even the First, whose regenerative abilities were the most formidable in the Shinobi World, could theoretically regrow severed limbs—but the price behind his rapid regeneration was clear from how young he had died.
Demons, however, were different.
Never mind the high-ranking demons among the Upper Ranks—even ordinary demons could regrow severed limbs with ease.
What was more, demons had astonishingly long lifespans.
As long as they kept consuming fresh flesh and blood, they could sustain their lives almost indefinitely.
Shinji remembered that in the original Demon Slayer timeline, Muzan Kibutsuji, the Demon King, had aged nearly nine thousand years after being dosed with a drug that accelerated aging—and still hadn't died immediately.
Nine thousand years!
Whatever else could be said, that lifespan put