Shoutout to LemonDog for joining the patron family. thanks a lot!

***

Mist Mountain.

As the name implies, the foot and the top peak of the mountain are usually covered in the blanket of heavy mist that would reduce the range of a normal human's vision. At the foot of the mountain, the mist village remained peaceful as ever.

Unlike other regions, this particular village never saw any demons after Sakonji Urokodaki moved in. Elders of the village knew the identity of the mysterious man and the fact that two youth kept running around the village with sweat covering their bodies affirmed their beliefs.

Which made the elders of the village like Sakonji and his disciples further. Although, many men would have to disagree when it came to liking the disciples. The dark-haired youth with crimson eyes and a kind smile touched everybody's heart with his actions. He would help any and everybody on a regular basis, the gentle smile on his face never receded while he was patient even with senile old elders, and his compassion really ignited the motherly nature of many single women.

Tanjiro Kamado, as the boy called himself, was an apple of the eyes of everyone within the village.

But.

That other disciple...

The hardworking men of the village had to operate the entirety of their willpower to not attack the youth named Nik.

Short dark hair, extraordinary features and a pair of enchanting violet eyes that went along with his tantalizing smile.

He wasn't any regular apple in the eyes of the village.

He was the forbidden apple that every woman of the village desired to take a bite of and also a rotten apple that every male member of the village wished to throw away.

But throw they cannot. Nik's behaviour was impeccable. Even his tantalizing smile had a hint of warmth and compassion that ruined the night of many women and the peace of their husbands and fathers. Of course, Nik would be darned if the men could actually notice him 'accidentally' touching a few soft spots of the women who would usually come around and chat with the duo.

They were pretty popular, Nik knew it and enjoyed it. Although Nik knew that he couldn't actually commit himself to these women, he still enjoyed his stay with them. After all, no matter how much he could entertain them, Nik was scheduled to at least leave this village in a year.

That is also one of the reasons Nik decided to stay his hand when it came to misleading young, unmarried women. As carnal as it felt, Nik still wasn't ready to let go of the little human heart within himself that actively resisted misleading the single women since he wouldn't be there for them. Of course, he could partner-up with them, but Nik also felt selfish enough to save the spots now.

He is in a world filled with a strange power that boasted high physical stats. Of course, he wished to partner-up with capable women who could also help him in gaining higher stats.

Due to this, the beautiful, prized housewives soon fell into the clutches of Nik's soothing hands and aroma. Not that he went too far with them. He would just ease his own desires a bit and not let them run rampage within himself.

There was just one problem, though.

"Nik-san, you are smelling extremely nice."

With a casual smile on his face, Tanjiro would keep on complimenting his fragrance. Through Sakonji, Nik already knew that Tanjiro had an outstanding sense to smell even the strangest of fragrance that could clearly mark the difference between human and demons.

"Thank you... I guess..."

Nik muttered and walked alongside Tanjiro. Both of them wore Kimono that belonged to Sakonji in his younger days when he hunted demons with extreme prejudice. 

Usually, the morning time was given to the duo to be utilised as they desired while they would then train for an entire day from swordsmanship to wrestling matches that Nik had as his first lesson while both, Tanjiro and Nik also had to venture to the top of mountain and then survive every night while they came back down. After all, to train their senses, Sakonji would fill the middle of the mountain with traps. 

Of course, Tanjiro stated that he could actually 'smell' the traps as he would clear them with a bit of difficulty while Nik would simply use his [Life Vision] to find out Sakonji's life signature and avoid the areas.

But still, there were times where he couldn't turn to his [Life Vision] and would fall into dangerous traps, slowly inducing him to grow cautious of his surroundings naturally.

Their days were plain. Nezuko did not wake up until now, causing Tanjiro no small amount of worry, but he would still smile, trying to hide his own desperation. After all, the goal he had set for himself— to turn Nezuko back into a human— was anything but easy. Of course, Nik also maintained an appropriate distance from the kind youth.

Nik did like him and his ideals, but he also understood that Tanjiro and he were simply not meant to mingle. Their thoughts were different and so were their virtues. As Sakonji preached on his first lesson, Tanjiro was the face of the faction within the Demon Slayers organisation that hated demons that devoured humans.

Although, Nik did not know Tanjiro well enough, this was at least, how Tanjiro portrayed himself to be. As long as demons don't kill, they are not an enemy. So, Nik could conclude that Tanjiro was one of the mild slayers with a pleasant personality.

Meanwhile, Nik continued his stretching exercise. Although, Nik admitted that he would end up skipping the exercise, he was still slowly building a proper control over his body alongside Sakonji's training that allowed Nik to get inspired in moving his own body while using his stats to a higher efficiency.

And finally, after two months of constant training, fellatios from generous housewives and survival within the mountain, Nik stood in front of Sakonji with Tanjiro by his side. Both of their hair had grown slightly longer and a stubble had once again touched their faces, but Sakonji still looked at them for how they looked when they first arrived and nodded.

"Tanjiro, when we first met—" Sakonji started as Tanjiro's expression grew a bit more determined, "— you were a mess. Indecisive, physically weak. But you had the heart, and I am extremely gratified by your progress. You have grown stronger, decisive and now, you look like a man."

There was a hint of amusement within Sakonji's tone as he looked towards Nik and continued. 

"On the other hand, Nik, you were the opposite. You had the strength, heart and decisiveness to slay demons. 

But your senses were weak and you had no experience. And I am proud to say that I have taught you."

Sakonji stepped forward and patted both of their shoulders and finally, his warm voice grazed past the duo's face.

"You both have grown, kids."

But before the duo could sigh in relief, Sakonji took his hands back and whispered.

"With this, your first part of training is completed. Now, I will be teaching the remaining part."

***

Within the plain hut, Nik and Tanjiro sat on one side while Sakonji sat beside Nezuko, letting his hands gently stroke her hair while he gazed at her face for a few moments.

"Demons, as you know, are still a mystery. But I know how they came to be, and I apologise for lying to both of you during our first lesson."

His voice was soft and soothing as he continued.

"Whether you are able to learn what I am going to teach you next does not restrict me from informing you the truth about demons and their weaknesses."

"First, the ancestors of the demons, or the First and the strongest demon, is was once a human who obtained these powers mysteriously at the price of feasting on human blood. The first demon has the ability to convert other humans into demons, but many fail the process known as demonification."

"Their weaknesses are low in number, yet, extremely fatal. Although, the demons boast physical enhancement far higher than us humans and also immorality, they are still flawed creatures.

Throw them outside the shade into a healthy daylight and they'll dissolve into ashes.

Butcher them until they have no strength, and they will still die."

"But!" Tanjiro immediately spoke with a frown on his face. "Isn't it suicide?! As you explained, the Demons are far stronger than us, how can we butcher them?"

"It wasn't a known method previously. But your friend here, Nik, and his noble young master, performed this very act and slew their first demon without any training."

Sakonji pointed out while Nik nodded. Although, he and Brian are also physically enhanced beings, it did not stop them from learning the methods of this world.

"Really? Nik-san?" Tanjiro looked back, his eyes flashing in astonishment and a little bit of awe. Even he had faced a demon alongside his sister, who was now in a coma, and understood how hard it is to actually slay one.

"Yes, we faced one two months ago. But I would like to point out once again that the demon was already hurt after the strange blast."

"Let's not diverge." Sakonji immediately placed a stop to all conversations and continued softly.

"Now, I will inform both of you about the third and final method humans have devised against the demons in this long fight.

The founder of the Demon Slayers had created a breathing technique that was slowly developed and diversified. This breathing technique allows us, humans, to wield a source of energy known as Hamon... or ripple energy."

Sakonji's hand finally left Nezuko's forehead and extended his hand towards the duo, a golden glow immediately covered his body as both, Tanjiro and Nik stood up, wide-eyed.

While Tanjiro was extremely surprised by the strange phenomenon and was truly worried about Nezuko as she laid right beside Sakonji, Nik was astonished due to the fact that the energy he could feel from Sakonji was way to stronger. It was as if he had released all his suppressed power and another revelation really shook him.

Despite the limit cap of 26 stats average, Nik finally understood the power system of this world.

The humans of his world actually combined their vitality and energy to burst out with strength that was way higher than the limit and this revelation made him feel a bit apprehensive against their enemies, the demons. If, even with the method to burst out with strength higher than the limit couldn't eradicate the demons, then, Nik didn't know how much of the threatening existence high-level demons actually were.

Soon, he regained his composure and sat down while waiting for Tanjiro to reclaim his calm.

"As you can see, this energy that you can feel is called Hamon, neutral Hamon to be specific. 

Hamon energy that we humans release could be considered a weaker version of the substance present in sunlight that destroys the demons. So, even if this energy hurts the demons, we still need to decapitate the demons using this energy alongside weapons made of special ores."

Sakonji concluded and looked at Nik and Tanjiro, who were listening to him calmly and a hint of a smile formed behind his mask as the golden energy soon rotated along his forearm and turned into bluish tidal waves that once again stunned his disciples.

"And... this is what you need to learn before leaving. Water Hamon Energy."

***

'Aww... shit! This world is an evolutionary one...'

Brian cursed. Fortunate or not, the threat of this world's beings finally shook Brian's heart as he, alongside a blonde named Zenitsu and another dark-haired boy, sat in front of an old man while his arm was covered in blue lightning that exuded vitality and destruction simultaneously.

'We should have chosen the demons...' 

Brian pursed his lips. He made a mistake, but he didn't feel too bad. They could still gain a lot from this world and if they manage to complete the missions, then their gains would be immense. Immediately, he regained his focus and continued hearing the explanation of his teacher while hoping that Nik doesn't lag behind.

As Nik was now, Brian could only help him slightly without giving him too much. After all, even with all his fortune, Brian didn't wish to invest in Nik if he doesn't prove himself to be a worthy demon. 

And just like that, the two demons started learning the art of demon-slaying.