The Nichirin Sword is the specialized weapon of the Demon Slayer Corps' swordsmen, also called the "Color-Changing Sword." Forged from sunlight-absorbing scarlet iron sand and scarlet ore, it possesses a unique ability to suppress a demon's regenerative powers, making it the only weapon capable of harming demons.
It is a sword meant solely for slaying demons.
Looking at the sword, Soma's body instinctively felt a wave of repulsion. Yet he stepped forward and gently took it in his hand.
The blade was engraved with four kanji: Destroyer of Demons. Its coloration was vivid, featuring a flame-like pattern along the length of the steel, while the hilt guard was forged in the shape of a flickering blaze.
From Soma's understanding of Nichirin Swords, the blade's color varies depending on the wielder's technique. For instance, a sword with flame patterns and a flame-shaped guard usually belongs to a demon slayer who has mastered the Flame Breathing style.
Gripping the hilt tightly, he could feel the heat radiating into his palm, accompanied by his body's natural aversion to the sword. Clearly, it contained power meant to exterminate demons.
Although he felt repulsion, Soma held the sword firmly. In doing so, the sword's effect slightly suppressed his demon instincts—the desire for human flesh that constantly gnawed at him.
In truth, because he had never consumed human flesh, his craving grew stronger with each passing day.
For weeks, he had forcibly suppressed the urge with sheer willpower, but the "bloodlust" within him grew day by day, causing immense mental strain. He had to remain constantly vigilant, and during the daytime, he even allowed parts of his body to be exposed to sunlight, injuring himself in a nearly self-destructive way to suppress the craving.
Feeling the hunger subside slightly while holding this weapon his body naturally hated, he let out a small sigh of relief.
These days, he had feared that, before finding the Blue Spider Lily, his will would be overpowered by the bloodlust, forcing him to cross a line he could never forgive himself for.
Soma stood in place, holding the Nichirin Sword, staring at the torn Demon Slayer Corps uniform and a set of fresh bones still containing blood. Clearly, this had been a demon slayer.
Yet the very swordsmen meant to hunt demons had become the prey, ultimately reduced to bare bones.
He lingered, staring at the skeleton for a long moment, before gripping the sword and venturing deeper into the cave.
Soon, he arrived at a small stone chamber inside the cave.
The cramped room reeked of blood. A demon sat there, its terrifying face showing signs of fatigue, yet its crimson eyes shone with excitement.
Across its chest was a massive wound, exposing a beating heart. Its arms and thighs also bore several deep wounds down to the bone.
Apparently, the demon had recently been in an intense battle. Even with a blade piercing its chest, the demon paid no mind to the injuries.
What would have been fatal to a human was inconsequential to the demon.
At this moment, he could see the flesh around the wounds writhing, almost visibly regenerating before his eyes.
Such regenerative ability, such immortality, demonstrated the sheer power and terror of demons. Even if an arm were severed, or the heart ruptured, a little time would be enough for rapid recovery.
Except for a decapitation by a Nichirin Sword, they were nearly unkillable.
"You really should have agreed to hunt with me yesterday. If you had, you could have tasted that delicious flesh too. The blood and flesh of a Demon Slayer Corps swordsman is nothing like that of ordinary humans. Now, I can feel my blood boiling—I can feel myself growing stronger…"
Seeing Soma enter, the demon lifted its crimson eyes, filled with excitement and agitation, tinged with a mocking curiosity, as if it wanted to see Soma regret coming.
However, the demon saw nothing in Soma that satisfied its expectation. This left it deeply annoyed, and fragments of memories from when it had once been human abruptly surfaced in its mind, causing a sudden, inexplicable discomfort and sorrow.
Though it possessed a powerful body, and had become more perfect than ever, an unfillable emptiness remained inside—an indescribable sadness that made the demon painfully claw at its hair.
Soma, watching the demon in this state, was already accustomed to it.
Demons, even in their perfected forms, have incredible regenerative abilities, immense strength, and nearly immortal bodies. They seem to be moving toward perfection, yet flaws always remain. Beyond fearing sunlight and being unable to resist the urge to consume flesh, they suffer various psychological issues—this is true not only for ordinary demons but even for the Twelve Kizuki. Most of these mental issues are tied to memories from when they were human.
"Hah… haha, no longer the weak creature I once was. Yet… those pitiful memories still occasionally surface," the demon said, wiping away tears that appeared without reason. Suddenly, it laughed loudly, rising to its full height.
"After consuming that Demon Slayer Corps swordsman's flesh, I feel stronger. Perhaps in the next 'Blood Battle for rank', I could even become a new member of the Twelve Kizuki."
"If I can just receive more blood from That Man, I will become truly perfect."
As it spoke, the demon's face showed longing, as if imagining that moment had already arrived. It seemed intoxicated by the thought.
After a long while, the demon snapped out of this state, fixing its gaze on Soma again.
"The last time I invited you to hunt with me, you refused. This time, I'll give you another chance. Cooperate with me, and I'll share some of the Demon Slayer Corps swordsmen's flesh with you. Trust me—the effects of their flesh are incredible. Your strength will increase, and once you experience it…"
"I'm not interested."
Soma shook his head, looking at the demon, whose expression darkened slightly. Hesitating for a moment, he spoke firmly: "You'd better restrain yourself. Once the Demon Slayer Corps targets you, given their swordsmen's fearless style, it won't take long before your neck is severed by a Nichirin Sword."
Hearing Soma's words, the demon recalled the swordsman it had killed yesterday. Even after being impaled through the abdomen by its claw, writhing in pain, the swordsman had still launched a frenzied attack, ramming its head and biting wildly. Thinking of that unrelenting frenzy, the demon felt a chill of respect.
But soon, it sneered at Soma:
"If we don't deal with them, do you think they'll spare us?"
Soma fell silent for a moment.
"Abandon the remnants of your human identity," the demon continued coldly. "Forget everything from the past. Remember—you are already a demon. Even if you never 'crave humans,' they won't listen to your explanation. If you don't become stronger, if you don't join the Twelve Kizuki, the Demon Slayer Corps will hunt us down. If your strength remains stagnant, no matter how you run, you'll remain prey. And compared to me, you might be the first to have your neck severed by their swords."
Laughing loudly, the demon added:
"Once I consume enough flesh, and my strength reaches the level of the Twelve Kizuki, even the Demon Slayer Corps' Pillars will become nothing more than my prey."