Eliminating the Demon Slayer Mark's side effects.
That was the second research problem Xia Xi posed to Tamayo.
What caught Xia Xi somewhat off guard was that, after hearing everything he knew about the Demon Slayer Mark,
Tamayo did not consider it something utterly impossible to achieve.
Because Xia Xi had also mentioned
that this pathogen could take two entirely different courses in different people.
Almost all the marked swordsmen of the Sengoku Period had died one after another within a few years.
Even the longest-lived among them had not made it past twenty-five.
Yet [Yoriichi Tsugikuni] had lived to old age.
From a rigorous standpoint,
if Tanjuro really did have a Demon Slayer Mark,
and had been born with it, as Xia Xi described,
that would prove Yoriichi Tsugikuni had not overcome the mark's lifespan limit through some sacred uniqueness.
At the very least, this Mr. Kamado, an ordinary man malnourished since childhood,
had lived into his thirties.
Far longer than those swordsmen with greater vitality and stronger physiques.
Then there had to be something hidden within his body
that could resist the mark pathogen's erosion of his lifespan... or rather, change its behavior.
As for this,
Tamayo, who very much wanted to see the Demon Slayer Corps' swordsmen grow stronger, poured every ounce of her energy into researching [Demon King Poison] and the [Demon Slayer Mark Virus].
Even her once-beloved afternoon tea breaks were abruptly cut much shorter.
And as Tamayo's workload grew heavier by the day,
Yushiro, on the other hand, found himself suffering and enjoying it at the same time.
His medical expertise was nowhere near Tamayo's, yet he had to participate in this cutting-edge new research.
The bowl-cut boy felt under immense pressure.
Every day, he had to spend at least several extra hours catching