In the year 2121, within an underground laboratory.
A white-haired, aging man with slightly trembling hands fiddled with some glowing components.
"Believe in yourself, I've gambled my entire life on this moment. Li Xing, you're the best!"
As Li Xing installed the final part, a mechanical voice echoed from the lab's broadcast system: "Data reception complete. Analyzing ambient energy, initiating absorption!"
"Is it... finally complete?" Li Xing was already exhausted, his breathing heavy. He suspected his life was nearing its end.
"Hold on, just one last step. I can't leave like this!" Li Xing shakily stood up, picked up two strange plugs, and inserted them directly into his body.
"Li Yun, enter my body!" Li Xing spoke to the screen before him.
Li Yun was an artificial consciousness Li Xing had created thirteen years prior, serving as the lab's terminal system.
"Digitization complete, transportation complete, system preparing for formatting!" the lab's broadcast announced its final words. A smile spread across Li Xing's face. A hundred years of time, finally drawing to a close.
"Thank you, Li Shi. I'm sorry, I can't let you remain in this world, nor can I take you with me."
At that moment, a mechanical voice sounded in Li Xing's mind: "Master, energy is insufficient. Please seek out sunlight to replenish energy and simultaneously collect Heavenly Dao data."
"Still not enough energy? Alright!" Li Xing, without further thought, began to walk outside, each step an immense struggle.
"So tired, so very tired! Am I dying?"
"Detecting rapid loss of Master's life force. Please persist, Master!"
Li Xing remained silent. Speaking another word might hasten his demise. He could only bend over and slowly make his way outside.
Upon contact with sunlight, Li Xing could no longer stand and collapsed onto the ground, already halfway to the gates of hell.
"Initiating Heavenly Dao digitization..."
Hearing this voice, Li Xing regained a sliver of consciousness. Though on the verge of death, he was elated.
"Then, let us begin mechanical ascension..." Li Xing finally closed his eyes, a smile still on his face.
"Initiating world search. World found. Initiating reincarnation!"
After an unknown period, Li Xing slowly opened his eyes. He felt an intense cold, accompanied by a faint scent of blood.
"Li Yun, did I succeed?" Li Xing, recalling his moment of death, was eager to know if it had worked.
"Master, digitization was successful. You have now arrived in another world, the world of Kimetsu no Yaiba from your memories."
Hearing this, Li Xing was overjoyed and wanted to jump up and celebrate, but suddenly realized he couldn't move. He felt like an infant.
"Li Yun, what's happening? I've become a baby. Where is my mother? Where is she?"
"Master, you were born of the Heavenly Dao and have no mother. However, you will still experience birth, aging, sickness, and death. Please complete the digitization of this world as soon as possible."
Li Xing understood. The inability to move meant he could starve to death. "Li Yun, can you accelerate my growth? To eighteen years old."
"Certainly, Master."
As the voice in his mind faded, Li Xing began to grow. In less than a minute, he transformed from an infant into an eighteen-year-old boy.
Li Xing waved his arms, feeling no discomfort. He felt as though he could take on ten, perhaps eight, former elite soldiers. It was excellent.
"Ugh, it's so cold, so cold! Is this the world of anime? Kimetsu no Yaiba? Snow? And the smell of blood? That must be Tanjiro's house up ahead?"
"Yes, Master. I can only reincarnate at the point where the plot begins in your memories."
Li Xing paid no mind to this. As long as he could transmigrate and reincarnate, it meant he had achieved mechanical ascension. He turned and walked towards the scent of blood.
He arrived at what was once Tanjiro's home. Bloodstains still marked the ground, and several mounds indicated burial sites. It seemed Tanjiro had already left. He had likely already encountered Giyu Tomioka.
"It's freezing. I should find some clothes first." Li Xing, hugging his arms, ran into Tanjiro's home. He rummaged through and found a few clothes, seemingly belonging to Tanjiro's father. Li Xing didn't bother thinking about whether they belonged to the deceased and simply put them on for warmth.
"Damn, I smell like charcoal. By the way, Li Yun, there's no advanced technology here. How can I digitize this world's Heavenly Dao?" Li Xing realized this world wasn't technologically advanced, making it impossible even for a genius like him.
"Master, ordinary people cannot perceive the Heavenly Dao. You simply need to sense the world with your near-death soul, as you did before. The rest will be handled by Li Yun."
"Are you kidding me? I have to die again? Can you at least preserve my last breath so I don't actually die?"
"Yes, Master. Please pick up the nearby blade and commit suicide!"
Li Xing: "..."
Can't you be more subtle? This is incitement to murder, a crime, you know.
"Fine, I trust you. Don't disappoint me." Li Xing picked up the blade from the ground and slowly moved it towards his neck.
Even knowing he wouldn't die, Li Xing was still nervous and couldn't help but swallow.
"Screw it, I'm going for it!" Li Xing gripped the blade with both hands, gritted his teeth, and forcefully slashed it across his neck.
Perhaps due to his excessive force, Li Xing felt nothing at first. Then, a sudden, sharp pain erupted from his neck, burning hot and tingling. Blood immediately flowed from the wound.
"It hurts so much..." Li Xing lost consciousness, similar to before, halfway to the gates of hell, with only a surge of energy from Li Yun sustaining his life.
"World Heavenly Dao perceived. Initiating digitization..."
After a long while, Li Xing slowly opened his eyes. He suddenly remembered what had happened and quickly felt his neck.
"Thank goodness, no scar. Li Yun, is the digitization complete?"
"Yes, Master. The digitization is complete~" A sweet, feminine voice echoed in Li Xing's mind, startling him.
"What the hell, why is your voice a girl's? Do you have this function too?"
"Master, after digitizing the Heavenly Dao, I seem to have gained the ability to think, though I cannot leave your soul."
Li Xing suddenly understood something, his eyes widening in realization. "Congratulations, Li Yun. You have gained true consciousness. From today on, you are no longer a system, but a spirit."
"It seems so, Master."
"Li Yun, since the Heavenly Dao has been digitized, are there any cheats? This world has demons, and I'm just a mortal, easily killed."
"Yes, Master. All powers in this world can be transferred to you."
Hearing this, Li Xing thought of a typical overpowered protagonist's life. He could already envision himself punching Muzan and kicking Kokushibo.
"What are you waiting for? Transmit them to me quickly. Whatever comes, comes."
"Initiating transmission~ Master..."