What is cognition?
Cognition is the process by which humans acquire, process, and apply information through mental activities such as perception, memory, and thought, encompassing the ability to understand and adapt to the objective world.
In summary, it is a complete system formed by what one sees, hears, thinks, and experiences.
In his previous life, Roy had watched Demon Slayer, empathized with its characters, experienced their joy, their sorrow, their resentment, and their anger, and thus left a deep imprint on his cognitive world.
He pondered, then sat up from the snow. A small cloth bag fell from his embrace, and a few candies rolled out. Only then did he remember that today was the full moon festival for his youngest sister, Kamado Hanako.
Due to his intervention, Tanjiro was no longer the eldest son of the family, and Rokuta, the youngest child born in the original story, had not yet been born. This meant that there were still two or three years until the plot began... Not only was his father, Kamado Tanjuro, alive and well, but even his grandmother, the white-haired old woman who often cuddled Tanjiro while stargazing, was still alive... This was very strange... In reality, Roy was the eldest son of the Zoldyck Family. In his cognitive world, he was still the eldest son of the Kamado Family. Perhaps it was this 'compatibility' that allowed him to open the door to [Demon Slayer].
Roy vaguely perceived the connection, bent down to pick up the candies one by one, and then began to check his physical condition.
First, 'Nen'... Roy tried to communicate with the qi within him, mobilizing it to surge towards his right index finger. A faint, milky white aura flickered. Although weak and not very noticeable against the white snow, it was truly there... This made him breathe a sigh of relief.
After all, this place, like the world of Hunter, was not a benevolent land, but a world where man-eating demons ran rampant. Having 'Nen' or not was crucial before mastering the Breathing technique and acquiring a Nichirin Blade.
Then, there was 'Assassination Arts'.
'Dark Step,' 'Limb Bend,' and 'Snake Living'... 'Dark Step': The Zoldyck Family's ancestral assassination footwork, focusing on the four elements of 'lightness,' 'floating,' 'deception,' and 'illusion'.
When moving, he was as light as a swallow, and when deceptive, he was like a dream... Roy took a step, moving as lightly as a ghost, sometimes to the east, sometimes to the west, his figure weaving through the old forest, making it impossible to discern his whereabouts, yet leaving no footprints in the snow. This... completely stunned a certain younger brother who was worried about his older brother's safety because it was getting dark.
Today was Hanako's full moon festival, and Father Tanjuro had instructed the eldest brother, Eiichiro, to go down the mountain early to make purchases. As evening approached, his figure was still nowhere to be seen... Kie, the mother of Eiichiro and Tanjiro, then sent Tanjiro, who had a dog's nose, to search for him.
Unexpectedly, Tanjiro found the person, but he himself was dumbfounded.
The naive and somewhat simple-minded younger brother, wrapped in a thick black and green plaid overcoat and a light purple scarf around his neck, stood blankly in the falling snow. A pair of beautiful amber eyes reflected Roy's dancing, ghostly figure, and his small mouth hung wide open, an 'Onii-chan' caught in his throat!
He kept repeating one sentence in his mind—Is this... still his big brother Eiichiro?
Yes... It's 100% big brother Eiichiro!
Eyes can deceive, but scent does not... Tanjiro's nose twitched, confirming that this was indeed Roy's scent. He quietly hid behind a large tree, only peeking out his head.
At this moment, after practicing Dark Step and getting used to his body, Roy didn't rest but immediately began to practice 'Limb Bend.'
This 'assassination technique,' in summary, was actually an advanced application of 'Dark Step.'
Compared to 'Dark Step,' it added an extra layer of confusing the opponent.
Roy took a deep breath and stepped out again, instantly creating a circle of afterimages from where he stood.
Killua had once used this technique against Netero during the Hunter Exam when he and Gon were playing ball on the airship, but the opponent's skill level was too high, and he was not someone a rookie who couldn't even use Nen Ability could 'touch'.
But that was Netero, the strongest human, not the inexperienced Tanjiro... Seeing this scene, Tanjiro's eyes widened again in an instant... He Counting on my fingers, instinctively tried to count how many older brothers there were... but unexpectedly, a sharp 'swoosh~' sound came—
A sharp hand blade, right by his ear, plunged into the big tree he was hiding behind!
'Snake Living': Forging hands into blades, invincible. When perfected to a subtle degree, it can penetrate mountains and rocks; when greatly achieved, it can penetrate refined iron; when perfectly achieved, it can cut through Nen objects... Roy had personally witnessed Sliva's hand blade cut through a fine samurai sword!
However, he was currently still in the rudimentary stage; being able to penetrate three inches into wood was already his limit. Any more would require time to hone... unlike killing intent perception, which one could learn a bit of through immersion!
That's right, as soon as Tanjiro found Roy, Roy also discovered Tanjiro!
He pulled his hand out of the tree that had been pierced through, smiling as he looked at this familiar yet newly encountered younger brother: "Mother sent you to find me, didn't she?... I'm sorry, I fell asleep just now and made you all worry."
Tanjiro looked at Roy's face, then glanced at his right hand. He was clearly still breathing, but his mind didn't seem to be back yet. He nodded blankly, then quickly shook his head like a rattle drum.
Seeing him like this, Roy chuckled and patted his head: "Do you have a lot of questions you want to ask?"
Tanjiro shook his head, then nodded.
Roy's smile grew wider... He said gently: "Today is Hanako's full moon festival. Let's celebrate for Hanako first, and then talk, okay?"
Tanjiro nodded vigorously.
Roy patted his shoulder, said no more, picked up the hoe with his foot, then bent down to carry the basket on his back, and walked leisurely towards home.
Tanjiro followed closely behind him, his head buzzing, until the moon rose above the treetops, casting long shadows of the two... only then did he stop... From this distance, through the wind and snow, they could already glimpse a few familiar small wooden houses.
From the eastward-facing one, wisps of cooking smoke rose, and faint sounds of children's laughter and adults' coughing could be heard. If a few dog barks and cat jumps were added, it would surely weave a warm picture of a mountain village.
"It's just a pity... this world really has demons... and in two or three years, this place will no longer exist..."
Roy murmured softly.
Tanjiro looked up at him in confusion: "Demons?"
Apparently, his older brother didn't want to explain too much. With another glance, he had already started walking towards home again.
Tanjiro paused, tightened the scarf around his neck, and quickly followed.
At this moment, hearing the commotion, the adults and children inside poked their heads out... Seeing Roy and Tanjiro, the children cheered... There was Nezuko, Takeo, Shigeru, and the youngest one still in swaddling clothes, Hanako, held in the arms of a white-haired old woman... "Big brother Eiichiro, you're back!"
"Yes... I'm back..."
Roy smiled in response, his gaze meeting that of the man sitting in a corner of the veranda.
The man coughed a few times, fiddling with a set of Japanese ritual attire. Seeing Roy look at him, he also smiled gently...