The demon's apprentice

Fade away

Heya! Just to clear any confusion or misunderstandings I'll say it right here at the start.

I grant my permission for pLord123 to post my fanfiction book to his/her YouTube channel FanFicFantasy(Monitised) As Long As Proper Credits are given. That's all, enjoy the fic!

-Author

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Kokushibo stared at the unconsious human boy. He wasn't dead, yet, but was close. He definitely knew that no matter how much he tried he couldn't win against an uppermoon all alone, however he still fought. The boy also had noticed him even when he was in his human disguise. He had walked past Kokushibo and glanced at him, with a very calm expression, but Kokushibo knew that the boy was suspicious.

He had great potential. The boy hadn't unlocked his true potential yet and it'd be a shame if he never got the chance to. The only way he would've gotten the chance as a human, would have been a lot of training. However, his time had been cut short. Even if he had had the time, he could've never reached the peak of his strengt. He would've always be held back by his mortal body.

Kokushibo turned to look at the demon girl who had fought along side with the human. She was stuck under some rubble and was trying her hardest to get out. Kokushibo heard from Muzan that one demon had managed to escape his grasp, just like Tamayo had. This girl must be it. Well better not let her live. Kokushibo sliced the demon girl with his sword and she started disintegrating. One less problem to deal with.

Kokushibo went a little closer to the demon slayer. The boy reminded Kokushibo of a certain someone. Yoriichi. Those earrings. That scar. Suddenly, the boy's eyelids twitched. Even with his arm missing, leg twisted in a awkward and uncomfortable postition, majority of his bones broken, deep wounds that continued to bleed, probably inner organ damage and dislocated joints, he still was able to pull himself back to consiousness.

"...So he... still tries... to fight...?"

The demon slayers eyes opened and immediately fell onto Kokushibo, then to the demon girls kimono, that had been left to the ground after she died. The boy most likely he knew what had happened to her as he started crying.

"Ne... Nezuko...." The boy muttered as he sobbed.

No more waiting. Kokushibo was now right next to the boy and he knew exactly what Kokushibo had in mind. The boy backed away the best he could while coughing up blood. He even tried to throw his sword at Kokushibo, but that attempt was sad as Kokushibo simply dodged it without even trying.

"St-Stay a-away-" The boy coughed out.

Kokushibo stabbed his katana through the boy's torso to keep him pinned to the ground. He coughed even more blood and slightly screamed. The boy coughed, gasped, panted, tried and tried to get some air in his lungs to at least stop the bleeding. His lungs were definitely half-destroyed. He was stubborn. He just refused to give up. Great potential indeed.

"Stay still... you'll only... damage your... body even more..."

The response Kokushibo got was a pathetic cough for air.

"Become a demon... and unlock your... true power..."

The boy slowly raised his arm that hadn't been cut off and tried to grab Kokushibo's blade, still piercing his side. He managed to grab it but wasn't able to pull it out. He had no strengt left in his body. While the boy was struggling against Kokushibo's sword, Kokushibo had already cut his hand. Once the boy realized that his expression changed from scared to absolutely terrified.

"N-n-No-" The boy coughed. "P-Plea-please no-"

That was all the boy could do before the blood was already pouring down his throat. The boy coughed, wheezed, gasped. He tried everything to spit the blood out. He tried turning his head to the side so the blood would simply be affected by gravity and not go down his throat. But that was simply fixed by Kokushibo holding his head in place.

The boy screamed in agony. It definitely hurt. The transformation always hurt. His eyes were unfocused and he probably broke his jaw by accident. Kokushibo awkwardly petted the boy's head, as if trying to soothe the pain. He had no idea why, he just did.

The human boy's nails started to grow longer and sharper, forming claws. They turned into more of a black color as they did. A pair of sharp fangs grew in place for his human teeth and his pupils became slitted. The sclera of his eyes turned into a dark red color, reminding a bit of blood. At first Kokushibo had thought his eyes had started bleeding. The boy's eyes started glowling slightly as they became brighter. His scar extended from the top of his forehead to his nose and another one appeared from his neck and reached his cheek. His foredead started to bleed from the middle and a new eye appeared. Another eye appeared on the opposite side of his face on his cheek. His arm slowly grew back and his wounds started to heal.

The transfromation was completed. The boy was now a demon. Kokushibo removed his sword from the boy's side and the wound healed. His other arm was also almost complitely healed. The boy had stopped screaming  and was now gasping for air. He slowly blinked back to reality and realized what had happened. He slowly sat up and looked at his hands, his missing one now fully healed.

He started to cry. The boy began to cry. The boy hid his face in his arms. Kokushibo could hear him mutter 'No no no...' as he sobbed into his hands. The boy still had his memories. If Kokushibo wanted for the boy to fully embrace his power, the boy needed to forget about his human life. There was two options. The boy had to eat a human, or the boy recived more blood. And so convenietly, a human appeared.

"Go and feed.... otherwise you... can't grow to... your full strengt.."

The boy shook his head and continued to sob. "N-no..."

"Let go of... your human life... it'll only... hold you... back."

"N-No!"

The human obviously tried to run away after seeing Kokushibo's extra eyes, but that attempt was cut short by a quick slash of Kokushibo's blade. The blood bleeding out from the corpse must've smelled delicous to the newly turned demon as he froze. He was still holding himself back.

"Go on... devour the... human. Satisfy... your hunger... Grow stronger."

Kokushibo could see that the boy was drooling. He was also breathing through his nose, which was a little odd at first until Kokushibo understood. The boy had a great sense of smell, and when a human turns into a demon their senses get stronger. This boy's sense of smell must've been as great as a demon's while he was a human, if not even greater. And now that he is a demon the smell of blood must be must be stronger than he was used to. The smell is driving him insane.

In an instant Kokushibo had brought the dead human next to the newborn demon. It was obviously too much for the starving demon as the second the corpse was next to him, he had bounched on it and started to devour it like a wild beast. The sound of flesh being ripped from bones and the sound of blood pouring everywhere was accompanied by the sound of the newborn demon grinding the meat in his mouth. Nothing else was heard. It was dead silent. Kokushibo stayed still and quiet, observing the boy loose himself in the bloodlust.

Soon the boy seemed to finish, and he slowly sat up next to the corpse, or what was left of it, and stared. He stared at the corpse with an empty gaze. The lower half of his face was covered in crimson blood and so were his hands. It was clear, the boy still could remember his human life, but it seemed like his brain was slowly locking away those memories. He slowly turned his head to look at Kokushibo.

"What... What happened..?" The boy muttered.

"You turned... into a demon."

"Demon..?" The boy repeated.

After Kokushibo had nodded he started crying again, this time he wasn't crying loudly. More like the tears were just spilling from his eyes and he had no idea how to stop them. He wasn't moving or making a sound. He sat still as the salty tears poured down his face, and fell to his lap. Kokushibo awkwardly reached out and placed his hand on the boy's shoulder.

"Let go.. of your humanity... and embrace... your true power..."

As the corpse next to them continued to bleed and the tears from the boy's eyes continued to spill, the boy's eyes slowly lose the bright and determined gleam and his memories fade away to the darkness. Whoever he used to be, is no more. Whoever used to be his friends and family, are strangers to him. Whatever he used to do, is useless. Whoever he trusted and loved, is gone from his life. Now he's a demon, and this man next to him is his mentor.