What is cognition?
Cognition is the process by which humans use mental activities such as perception, memory, and thinking to obtain, process, and apply information, encompassing the understanding and adaptation to the objective world.
In summary, it is a complete system formed by what is seen, heard, thought, and experienced.
In his previous life, Roy had watched Demon Slayer, immersed himself in the characters, and experienced their joys, sorrows, grievances, and angers, leaving a deep footprint in the cognitive world he knew.
He pondered, sat up from the snow, and a small cloth bag fell from his arms, spilling a few candies, reminding him that today was his youngest sister Kamado Hanako's Full Moon Festival.
Due to his involvement, Tanjiro was no longer the eldest son in the family, and the youngest child, Ryota, from the original story, had not yet been born, which means... there were still two to three years before the start of the plot...
Not only was his father Kamado Tanjuro still alive, but even his grandmother, the white-haired old woman who often watched the stars with Tanjiro, was still alive...
This was very intriguing... In reality, Roy was the eldest son of the Zoldyck Family, and in his cognitive world, he remained the eldest son of the Kamado Family. Perhaps it was precisely this "compatibility" that allowed him to open the door to [Demon Slayer].
Roy vaguely perceived the connection within, bent down to pick up the candies one by one, and then began to check his physical condition.
First is "Nen"...
Roy tried to communicate with the energy within his body, directing it to surge towards his right index finger. A milky halo wavered; although weak, it was truly present, not so conspicuous against the backdrop of the white snow...
This made him let out a sigh of relief.
After all, just like in the world of Hunter X Hunter, this was no paradise either, but a world rampant with man-eating evil ghosts. Having Nen or not, without mastering the Breathing Technique, and obtaining a Nichirin Sword, was crucial.
Then, it was the "Assassination Techniques".
"Dark Step", "Limb Curvature", and "Snake Life"...
"Dark Step": A step technique passed down through generations in the Zoldyck Family, focusing on the four elements of "light", "floaty", "bizarre", and "phantom".
When moving, light as a swallow, bizarre as a dream... Only to see, Roy stepped forward like a ghost, gracefully moving sometimes to the east, sometimes to the west. His figure shuttled through the old forest, leaving no trace in the snow while making one's shadow indistinguishable, directly stunning a certain younger brother who was worried about his Oni-chan's safety due to the darkness.
Today was Hanako's Full Moon Festival, and Father Tanjuro had ordered the eldest brother Eiichiro to go down the mountain to shop early. As evening approached, he was still nowhere in sight... Kie Kamado, Eiichiro, and Tanjiro's mother, sent Tanjiro, who had a nose like a dog's, to find him.
Unexpectedly, Tanjiro was found, but he himself was also stunned.
The naive and somewhat straightforward younger brother was wrapped in a thick black and green checkered coat with a light purple scarf around his neck, standing dumbfounded in the heavy snow, his beautiful amber eyes reflecting Roy's ghostly figure fluttering. His small mouth opened wide, and the word Oni-chan got stuck in his throat!
His heart kept repeating one sentence—Is this... still his big brother Eiichiro?
Yes... it was definitely big brother Eiichiro!
Eyes can deceive, but scent cannot... Tanjiro's nostrils twitched, confirming it was indeed Roy's scent. He quietly hid behind a big tree, only poking his head out.
Having just practiced Dark Step and familiarized himself with his body, Roy did not rest and directly began to practice "Limb Curvature".
This "Assassination Technique" is essentially an advanced application of "Dark Step".
Compared to "Dark Step", it added an effect to confuse the opponent.
Roy took a deep breath, stepped out again, pulling a circle of afterimages from the starting point of his stance.
This move, which Killua had used on the airship to snatch a ball with Gon during the Hunter Exam against Netero, was witnessed by Roy. However, the opponent's rank was too high for a novice like him who was still unfamiliar with Nenryoku to challenge.
But that was the strongest human, Netero, not the inexperienced Tanjiro...
Seeing this scene, Tanjiro's eyes widened again... He dumbly counted his fingers, subconsciously trying to figure out how many brothers there were... only to hear a sharp sound—
A sharp hand blade slid past his ear and plunged into the tree he was using as a hiding place!
"Snake Life": Forge hand into blade, invincible and unstoppable, at entry level can penetrate rock, great success can penetrate refined steel, at perfect can cut through a Nen Device...
Roy had witnessed Silva cutting through a fine Samurai Sword with a single hand blade!
But at this point, Roy was still in the elementary stage; penetrating three inches of wood was his limit. Any further progress required time to hone... Unlike Sensing Killing Intent, which he could absorb a little from constant exposure!
Indeed, the moment Tanjiro found Roy, Roy had also discovered Tanjiro!
He pulled his hand from the tree already pierced, looking at this familiar yet first-seen brother with a smile: "It was Mother who sent you to find me, right... Sorry, I fell asleep just now and made you worry."
Tanjiro looked at Roy's face, then at his right hand. Although the person was breathing, his spirit seemed yet to return. He nodded dumbly and then shook his head vigorously.
Seeing his appearance, Roy amusingly patted his head: "Do you have many 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 her first, and then we'll talk, okay?"
Tanjiro nodded vigorously.
Roy patted his shoulder, saying no more, tapping with his toes to grab the hoe, bent over to carry the basket, and strolled in the direction of home.
Tanjiro followed closely behind him, his head buzzing, until the moon rose above the treetops, stretching their shadows long....
Finally, they stopped their steps...
From this distance, through the snow and wind, they could already see a few familiar small wooden houses.
The eastern one had a gentle smoke, with faint sounds of children's laughter and adults coughing. Paired with a few barks and meows, it could certainly paint a warm mountain village scene.
"It's just a pity... this world truly has ghosts... in two to three years, this place will be gone...."
Roy thought to himself.
Tanjiro raised his head, looking at him doubtfully: "Nii-san?"
Roy moved his footsteps, and with another glance, he had already set off towards home again.
Tanjiro tightened the scarf around his neck and quickly caught up.
Meanwhile, hearing the commotion, the adults and kids peeked out of the house... Seeing it was Roy and Tanjiro, the children cheered joyfully...
There was Nezuko, Takeo, Mao, and the smallest one still swathed in a quilt, held in the arms of a white-haired old woman... Hanako....
"Big brother Eiichiro, you're back!"
"Yes... I'm back...."
Roy responded with a smile, his eyes meeting those of the man seated in a corner of the veranda.
The man coughed a few times, fiddling with a set of Japanese ceremonial clothes. Seeing Roy look over, he gave a gentle smile as well...