Ijin stood outside on the dark and empty street, the raindrops pelting his umbrella like tiny bullets. His eyes scanned the area, searching for any sign of movement. He needed to find out who or what was watching him.

Suddenly, he heard a rustling in the bushes nearby. As he watched, a figure emerged from the bushes, illuminated by a nearby streetlamp.

A monster had appeared.

Eyes gleaming with malice. His skin was a sickly gray, stretched taut over his bones, with deep black veins pulsing just beneath the surface. His long, jet-black hair hung in tangled strands around his face, which was twisted into a grotesque snarl. His mouth was filled with razor-sharp teeth, and his eyes glowed a sinister red. From his forehead sprouted two horns, jagged and sharp, jutting out like the devil himself. His fingers ended in wicked claws, sharp enough to rend flesh from bone with ease. As he flexed his muscles, his body seemed to contort and shift, as if he was almost too powerful for his skin to contain. This was a creature of nightmares, one that could be found in the darkest depths of hell.

Ijin's eyes widened in terror as the monster approached him with eyes gleaming with a predatory hunger as if it was ready to pounce on its prey.

"Well, well, well," the demon hissed. "What do we have here? A human, all alone in the rain. How delicious."

Ijin tried to back away, but his legs felt like they were made of lead. Fear clawed at his chest, but he refused to let it show on his face. The monster stepped closer, its claws clicking ominously.

The boy took a deep breath, trying to calm his racing heart. He knew he was in danger, but he couldn't let the demon see his fear. He faced the creature head on, his expression stoic and emotionless. Given that this monster referred to him as a human, it implied that the abomination standing before him wasn't human. That much was believable.

"You talk as if you want to eat me," he said, his voice calm and level despite the terror that gripped him.

The monster's lips twisted into a sadistic grin as it heard the boy's words. "Oh, but I do want to eat you," it said, its voice dripping with malice. "You see, in this world of machines and metal, humans have become so… diluted. But you, my dear boy, you're a pure specimen. No cybernetic enhancements, no artificial parts. Just flesh and blood, waiting to be devoured."

He took another step closer, its claws glinting in the dim light. "And trust me, your flesh will taste all the better for it," he hissed. Suddenly, the monster bolted towards his prey, claws raised to shred the boy to pieces.

Ijin lowered his umbrella, holding it out like a flimsy shield to hide behind.

The umbrella was no match for the monster's ferocity, and with a swift smack, it was swatted away. But just then, the monster momentarily lost sight of his prey, his gaze sweeping over the dark, rain-soaked street. But as he lowered his eyes, he saw the human squatting low, sword in hand. Moments later, he let out a guttural scream as he fell to the ground with a loud, wet smack against the concrete. "Ugh…," he grinded his teeth, realizing his ankles had been cleanly sliced through, leaving him no feet to stand on.

"Where the hell did that sword come from?" the monster growled, eyes flickered towards the fallen umbrella, noticing that the handle was missing. "A concealed weapon?" he growled, his surprise quickly turning to anger. He had been misled into believing that the boy was unarmed when in fact he had been holding a weapon this entire time. "You little bastard!" he snarled, his claws extending in a show of aggression.

Ijin stood over the grotesque form on the ground, his eyes cold and calculating. "Now then," he said in a chillingly calm tone, "why don't you tell me what the hell you are before you bleed out?"

The demon let out a harsh laugh, his eyes glinting with malice. "You don't seem to understand," he said, his grin widening. "Something like this means nothing to a demon!"

Suddenly, the demon's wounds began to regenerate, and he quickly clambered to his new pair of feet, his body twisting into a predatory crouch. Ijin's shock quickly turned to fear as he realized that not only did this creature mentioned the word 'demon' just like Nezuko, but it possessed regenerative abilities far beyond anything he had ever seen before.

The demon lunged at Ijin with blinding speed, his claws gleaming in the rain. The boy leaped to the side, barely avoiding the attack and keeping his distance.

With a sense of urgency, Ijin quickly deduced that his opponent's strength and agility far surpassed that of a human. The fact that the demon had the ability to regenerate its wounds in mere seconds only heightened his sense of alarm. He knew that he needed to act fast before the monster becomes too much of a problem. Despite his desire to learn more about these so-called 'demons', he knew that he could not afford to take any risks in facing such a formidable foe.

Decisively, Ijin lunged forward with a precise thrust of his thin and light blade, which pierced the demon's heart. But even as the cold metal slid through the monster's chest, it continued to charge towards him, its hand seizing Ijin's right wrist with an iron grip. The demon's other hand stiffened its fingers which speared into the boy's abdomen with its claws. The pain was excruciating, but Ijin gritted his teeth and tried to remain focused, fighting through the agony to find a way to overcome this relentless adversary.

What the hell? I stabbed him in the heart. How is he still alive and well? Are his organs located differently than a human body?

Click!

"ARUGH! UGH!" The demon suddenly convulsed as an electric shock coursed through its body.

Ijin pulled his electric blade out of the monster's chest and swung it in a deadly arc with a murderous glare, beheading the demon in a single stroke. The grotesque head rolled away, leaving its body behind.

"Haah… Haah…," breathless and shaken, he deactivated his electric blade and covered the wound on his abdomen, feeling the warmth of his blood seeping through his clothes. But before he could catch his breath, the headless demon's body lurched forward, throwing a punch at his face. Ijin managed to lurch to the side and dodge the attack, but his shock only deepened.

WHAT THE HELL!?

He reacted on instinct, delivering a powerful front kick that sent the decapitated body tumbling to the ground. As he watched in disbelief, the head spoke to him in a haunting voice, "You're no ordinary human."

"How are you still alive?" Ijin asked in disbelief, struggling to comprehend the demon's physiology.

"I already told you. Something like this means nothing to a demon," said the head which the headless body picked up and reattached it to its neck. Even the wound in its chest had stopped bleeding. "We demons are immortal. We don't age, we don't get sick, and we can regenerate from any wound."

Ijin's mind was reeling. So, this was what a demon was. Was Nezuko like this too?

He knew that he needed to be more cautious and strategic if he wanted to take down a creature like this. Every fiber of his being was begging him to run away, but he knew that would be pointless. He wouldn't be able to outrun this demon. And if they change location now, it would risk bringing others in harm's way. He had no choice but to stand his ground and fight. With a determined look on his face, he faced the demon and spoke with a cold, steady voice, "I see. Well, it looks like I'll need to come up with a different approach to defeat you."

"You still think you have a chance?" The demon grinned sinisterly.

As the demon charged at him again, Ijin sidestepped and delivered a swift slash with his blade, cutting deep into the monster's shoulder. The demon grunted in pain and stumbled backwards, and the swordsman took advantage of the opportunity and continued his assault, striking the demon repeatedly with precise and deadly strikes.

Despite his best efforts, however, the demon's regeneration was too powerful to be overcome by mere physical force. With each wound Ijin inflicted, the demon's body would heal almost instantly, leaving him seemingly unscathed. Frustration and fear began to creep into Ijin's mind. Was this demon truly invincible?

The static hum of Ijin's blade filled the air as he eyed the demon, ready to strike. In one swift motion, he lunged forward, the tip of his weapon puncturing through the demon's right eye socket, piercing the brain and sending an electrifying shock through the central nervous system. "ARUGH!" The demon convulsed and spasmed, writhing in agony as his brain was fried from the inside out.

Upon withdrawing his blade, the boy took a defensive stance, ready for the demon's retaliation as he observed his immortal foe gradually regenerating his right eye.

"Damn you!" cried the monster as he lunged forth viciously at the boy who evasively backed away in a zigzagging pattern.

With any emotion on his face, the boy had confirmed the unfortunate truth, "So even your brain can be regenerated." He knew that there were many examples of animals capable of regeneration. Among those, only a few could regenerate a brain such a worm or a starfish. But the most frightening aspect of this demon's regeneration was its speed. Ordinarily, it should take months for such a process amongst animals. To accomplish this in mere seconds was unfathomable, defying all logic and reason.

Having targeted virtually every vital spot he could think of, Ijin had failed to locate any weak spots on this freak of nature. Disheartened, he flung his sword forward; the blade impaling at the center of the demon's chest. The monster convulsed once again, trapped in a constant state of electric shock with no means to remove the sword on his own.

Quickly, the boy took out his smartphone in his pocket and began opening up an app on his screen. He let out a heavy sigh of disappointment. This was an unwinnable battle.

Turning away from the demon, Ijin began to walk down the street. In the distance, a bright light shone through the darkness. It was a silver car, moving at breakneck speed without a driver. With a sickening thud, the car collided with the demon, obliterating the monster into a bloody mess.

"And there goes my car…," he grumbled under his breath.