Chapter 70: The Demon Who Didn't Say a Word
During his patrol that night, one unlucky demon's hunt was cut brutally short when it crossed paths with Kanzaki Akira.
What followed was a live, gruesome demonstration of the term "dismemberment."
From its perch on a nearby branch, Akira's Kasugai crow, Ink Shadow, watched the proceedings, trembling from its head to its tiny claws.
'Is anyone going to do something about this?' the crow thought in a panic. 'Someone is terrorizing a small animal down there!'
Though the display carried a faint undercurrent of Akira venting his frustrations, he harbored no twisted hobbies like torture. His methods, while grim, served a single, calculated purpose: to utterly strip the demon of its ability to resist.
His goal was to test a new medicine.
Specifically, the latest poison developed by Kochou Shinobu, to observe its effects on a living demon.
It was a grim necessity. Akira knew that Muzan could peer into the memories of any demon connected to him, so capturing one and bringing it anywhere near the Butterfly Mansion was unthinkable. Other methods, like drawing blood or taking tissue samples, were equally useless; such materials would simply turn to ash the moment the demon perished. He recalled that a special device was needed to preserve demon blood, a tool he knew a certain doctor was likely already working on.
With the Demon Slayer Corps' current resources, building a secure, remote prison to hold demons was also an impossibility. Most slayers simply applied Shinobu's poisons to their blades, meaning any feedback they provided was vague at best. They could only report that the poisons made killing demons "easier," but offered no specifics on dosage, reaction time, or the nature of the effect. This kind of anecdotal evidence, while better than nothing, was of limited use to Shinobu and her father in their research.
, the strategy of wounding a demon without killing it was beyond the capabilities of an ordinary swordsman. When faced with a monster that could kill you in an instant, delivering a fatal blow was the only logical course of action to ensure one's own survival.
Thus, the grim task of weakening a demon just enough to serve as a test subject fell to Akira alone. He was one of the few with the confidence and skill to discern whether a demon was truly incapacitated or merely feigning weakness, waiting for a chance to strike.
He didn't take any chances. After severing its limbs, he had shaved several thick branches into sharpened stakes, pinning the demon's torso and regenerating stumps to the forest floor. This not only immobilized the creature but also guaranteed him ample space to react should it somehow manage a counterattack. More, this setup allowed him to observe the poison's effect on a demon's vaunted self-healing abilities.
With the subject secured, he began the test. He administered the toxin with a syringe, injecting it directly into the demon's flesh.
The effect was immediate and horrific. The skin around the injection site began to ulcerate, weeping a dark, foul-smelling fluid. The decay spread with terrifying speed, crawling across the demon's body like a ravenous blight. Based on the violent, full-body convulsions that wracked its pinned form, the poison was inflicting unimaginable agony.
Finally, after a long, silent struggle, the evil creature disintegrated into dust.
It wasn't that the demon was tough enough to endure such a toxin without screaming.
It was simply that Akira had found its guttural roars distracting. While securing its limbs, he had taken the liberty of driving another wooden stake straight through its throat and deep into the earth, silencing it permanently.
With that, the successful development of a poison capable of killing a demon was confirmed. Months of tireless work by Shinobu and her father had yielded one more weapon in humanity's arsenal.
However, the upper limits of this poison's efficacy remained unknown. That would require more testing.
"Next time, I'll try applying it directly to my blade," Akira muttered to himself, carefully recording the results in a small notebook. "See how the dosage impacts the effect."
His notes were constrained by the primitive experimental conditions and his own limited medical knowledge, but they were a world away from the vague feedback of other Corps members.
The best method, of course, would be for Shinobu or her father to observe the tests firsthand. But Akira would never allow them to take such a risk, even if it meant slowing down their progress.
As he thought about experts in demon-related pharmacology, another name came to mind.
'I'll have to find time to visit Asakusa and look for her,' he resolved.
Although demons possessed few fatal weaknesses beyond sunlight and decapitation by a Nichirin Blade, they were not invincible. If they sustained enough injuries in a short period without being able to consume human flesh to replenish their energy, they would eventually weaken and die.
The demons used for the Final Selection on Fujikasane Mountain were a prime example. They were all captured and repeatedly wounded by high-ranking slayers to weaken them before being cast onto the mountain.
Theoretically, as long as one inflicted enough damage fast enough, a demon could be worn down to death without ever severing its neck.
But this was only a theory.
Any slayer skilled enough to achieve such a feat was more than capable of simply taking the demon's head. And those who couldn't even manage that stood no chance of winning a war of attrition—a battle that played directly to a demon's strengths.
However, there was a unique power in this world that could dramatically amplify the damage a Nichirin Blade dealt to a demon: the Crimson Red Blade.
Alongside the Demon Slayer Mark and the Transparent World, it was one of the three ultimate tools for annihilating demons.
The principle was to raise the temperature of the Nichirin Blade to an extreme degree, either through sheer grip strength or by clashing it against another blade. This intense heat would further stimulate the solar energy stored within the ore, causing the blade to glow a brilliant, burning red.
An injury from a Crimson Blade was devastating. Ordinary demons were completely unable to regenerate from such wounds, and a few slashes were enough to make them crumble from their injuries.
Even Lower Rank demons found it incredibly difficult to deal with. It was only a matter of how many more hits they could take compared to their weaker brethren.
Upper Rank demons could eventually recover, but the wounds would sear them with an unbearable burning pain. Their regeneration would be significantly slowed, and the energy consumed in the process would be immense. If wounded enough times by a Crimson Blade, even an Upper Rank would perish.
The ultimate example was Yoriichi Tsukiguni. The scars his Crimson Blade left on Muzan continued to burn and cause the Demon King pain hundreds of years later.
Akira's thoughts connected the new poison to the Crimson Blade. Both offered a path to killing demons without the need for decapitation, and more, neither required sacrificing one's lifespan like the Demon Slayer Mark.
Therefore, poison and the Crimson Blade would become the two main pillars of his future strength development. The power boost from the Mark was a last resort, a final option to be used only when his life was truly on the line.
Besides the Crimson Blade, the other legendary tool, the Transparent World, could also be activated without a cost to one's life. It was a state of perception that allowed a user to see through an opponent's body, observing the flow of blood, the flexing of muscles, and the contraction of lungs. This allowed them to perfectly predict their enemy's movements and attacks. In this state, one's mind and body were so highly focused that not a single shred of energy was wasted.
But compared to the Crimson Blade, the difficulty of accessing the Transparent World was exponentially higher.
More accurately, Akira had no idea what the specific conditions for unlocking it were. He only knew that it required an immense foundation of strength, deep comprehension, and a rare, innate talent.
As far as he knew, there were only two beings in the world who currently possessed this ability: Upper Rank One, Kokushibo, and a humble charcoal seller named Kamado Tanjuro.
The former would never deign to guide a human on how to achieve it. The latter was someone Akira couldn't easily approach for guidance—at least, not yet.
Therefore, he temporarily focused his attention on the Crimson Blade, whose activation requirements were far clearer.
To heat a Nichirin Blade, the original story mentioned three methods: immense grip strength, clashing blades with another slayer, or using Nezuko Kamado's Blood Demon Art. Akira was already brainstorming other possibilities.
He couldn't guarantee he would have a teammate strong enough to clash blades with him every time he faced an Upper Rank.
, he was determined to prevent the tragedy of the Kamado family, which meant the option of using Nezuko's Blood Demon Art had to be excluded from his plans.
But if he succeeded in saving them… he could consult Kamado Tanjuro about the Transparent World. He could strive to master that powerful counter to the Upper Ranks as soon as possible.
'Good,' he thought with a flicker of grim satisfaction. 'Reason to save the Kamado family, plus one.'
In the end, the night passed without further incident, save for one unlucky demon that became a sacrifice for the birth of a new demon-slaying art.
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