For hundreds of years, it has been said that after sunset, a terrifying monster roams the earth.
They are called "Demons." Demons feed on humans, are immortal, and can recover from any fatal injury. Even if chopped into pieces, they can continue to live.
Only the sunlight of the day can completely kill a Demon.
Since Demons exist in the world, it is only natural that a group of human swordsmen dedicated to slaying these evil creatures has emerged. Over the centuries, they have come together to form an organization known as the Demon Slayer Corps.
Although not officially recognized by the government, they continue to carry out their mission of hunting Demons to this day, protecting the peace of the world and striking fear into countless evil Demons.
The Demon Slayer Corps wields a powerful weapon—the Nichirin Blade.
This weapon is forged from a miraculous material and seems to carry the energy of the sun.
When a swordsman uses a Nichirin Blade to behead a Demon, the immortal creature will instantly turn to ash.
From Karasuma, Shinichi learned a great deal and gained a general understanding of the world today.
Moreover, Shinichi also discovered a crucial piece of information, it seems that the birth of all evil Demons can be traced back to one person, or rather, to that person blood.
It is that person blood that has given rise to the countless evil Demons in existence today.
As for who that person is, Karasuma dared not speak the name, no matter what.
But Shinichi already had a rough guess.
He thought of those dark red eyes from that night, the man named Muzan...
*****
"Run! Run away!"
In the dark forest, a figure was frantically fleeing through the bushes, looking back in terror under the moonlight.
The figure had sharp horns on its forehead and fangs in its mouth—clearly, it was a Demon.
But what was behind the Demon? What could possibly terrify an almost immortal Demon to such an extent?
"What kind of monster is that? It's too terrifying! Even though we're both Demons, that bastard can kill other Demons! Run! I must get away from here before dawn!" the horned Demon muttered in fear.
Boom!!
A sudden explosion startled the horned Demon.
A cloud of dust rose in front of it, and the shockwave knocked it to the ground.
By the time the horned Demon stood up again, a figure radiating intense heat had emerged from the dust.
The figure exposed skin glowed red, its black pupils narrowed into vertical slits, and its sharp fangs slightly protruded from its lips. The black claws on its fingertips gleamed coldly and in its right hand, it held a mangled head.
A small, unremarkable green branch pierced through the shattered skull of the Demon.
"Blood Demon Art: Life Drain!"
Under the horrified gaze of the horned Demon, the head in Shinichi hand rapidly withered until it was crushed into dust.
"P-please, sir! I-I promise I won't eat humans anymore! Spare me!" the horned Demon trembled and begged desperately.
Before the horned Demon could react, a black lightning bolt struck it from behind.
"ARRGGGHHHH!!!"
Sizzle! Sizzle!
The horned Demon let out a piercing scream, writhing in agony.
A small figure clung tightly to the back of the Demon.
The transformed Shiba Inu, Maru-ni, opened its mouth and fiercely tore into the Demon back with sharp teeth.
Crack!
As Shinichi stomped down, the withered body of the Demon disintegrated into ashes.
The reddened skin on Shinichi body gradually returned to normal and the vine in the palm of his right hand retracted.
"The fifth one."
Shinichi silently counted in his heart.
It had been over a month since he transformed into a Demon and during this time, he and Maru-ni had hunted down five Demons.
Arf arf!
Maru-ni, with blood still clinging to its mouth, wagged its tongue and circled around Shinichi, clearly seeking praise and looking quite pleased.
Perhaps because Maru-ni had been transformed by Shinichi blood, a strange connection had formed between them since then.
Shinichi could sense Maru-ni thoughts and feelings.
Of course, although Maru-ni was quite intelligent, it was still just a Shiba Inu, so Shinichi could only pick up simple thoughts like "happy," "master," "hungry," "bored," "itchy teeth," and so on.
Even so, this connection allowed the Demon and the dog to work together seamlessly, easily hunting down five Demons.
After starting a small campfire and roasting the rabbit that Maru-ni had caught, Shinichi stared at the sizzling meat, his mind wandering.
The roasted rabbit wasn't for him, of course.
Since becoming a Demon, Shinichi could no longer eat any food, not even water.
Only Maru-ni remained unaffected, wagging its tail as it circled the fragrant rabbit meat.
Maru-ni situation was somewhat unique.
Rather than becoming a Demon dog, it was more accurate to say that Maru-ni had gained Demon-like abilities.
Shinichi Demon blood seemed to have merely attached itself to Maru-ni, only activating during battles.
As a result, Maru-ni could still eat normally and walk in the sunlight, two things that Shinichi envied deeply.
Thanks to his Blood Demon Art—Life Drain—Shinichi could sustain himself by hunting other Demons, eliminating the need for food.
However, over the past month, Shinichi had become increasingly uncertain about his own identity. He often found himself wondering: was he still a Demon, or was he still human?
While Shinichi was lost in thought as usual, Maru-ni had already finished the entire roasted rabbit and was now rolling around on Shinichi lap, begging for attention.
"Take it one step at a time" Shinichi sighed inwardly, reaching out to rub Maru-ni round belly.
*****
The sun rose, its warm rays awakening the earth and the villagers of Shirai Village.
This was an ordinary small village at the foot of the mountain, where dozens of households relied on the nearby Shirai Mountain for their livelihood.
The mountain was named Shirai because it was once home to a famous white ancient well.
Legend had it that the water from the well was sweet and refreshing, and tea brewed with it was said to be exquisite, even favored by daimyos during the Heian period.
However, the white well had dried up centuries ago, and the tales of Shirai were now just stories told by the village elders.
"Hey, Yamada, are you heading into the mountains today?"
"Sigh, I have no choice. My family's food supply is almost gone. If I don't go into the mountains, my wife and children will starve."
"But there are Demons on the mountain! Hayakawa, Maeda, Matsui... none of them returned from the mountain. The only one who made it back, Hirane, went mad, constantly shouting about seeing Demons."
"What can I do? The police at the station don't dare go up the mountain. I have no choice!"
At the village entrance, two men dressed as woodcutters were talking with worried expressions.
As woodcutters who relied on chopping wood for a living, not being able to go up the mountain was equivalent to cutting off their livelihood.
Although there had always been legends of Demons on Mount Shirai, recently, over a short period, more than ten villagers had gone up the mountain and never returned.
The elder in the village all said it was the work of the Demons.
It was at this moment that the two worried woodcutters noticed a group of young men from the village gathering together, marching toward them with great momentum.
Most of these young men were carrying various weapons—hatchets, bows and arrows, throwing darts, and even long naginatas.
One of the woodcutters, sensing trouble, quickly stepped forward to stop them and shouted at the leader.
"Jiro! What are you all planning to do?"
The young Jiro replied confidently "Mr. Yamada, we've heard the stories about the mountain Demons for a long time. But those are just tales old man Heiji and others tell to scare children. We think the attacks on the mountain are just wild animals. We're prepared, and today we'll definitely solve this problem for the village! Don't worry, Mr. Yamada, soon everyone will be able to go up the mountain freely again."
The woodcutter Yamada looked at the naive Jiro, both angry and anxious, and scolded.
"Nonsense! Whether there are really Demons or not, even if it's just wild animals, do you think a bunch of inexperienced kids like you can handle it? Go back! Don't meddle in this! This is a matter for us adults!"
Amid the commotion, no one noticed the small Shiba Inu wagging its tail on the path near the village entrance, its fluffy ears perked up as if listening to something.
In a dark cave, Shinichi opened his eyes, processing the information he had heard through Maru-ni' body.
"Mount Shirai, mountain Demons? Hmm..."
Shinichi pondered, weighing the truth of this information.
Over the past month, Shinichi had hunted five Demons and the intelligence had mostly come from overheard conversations like today.
But Japan has always been rich in ghost stories, so most of the Demon-related rumors Shinichi heard were inaccurate.
Could this one also be false?
On Mount Shirai, were the perpetrators wild animals or Demons?