The Demon's Apprentice || Rewrite

Rage

As Kokushibo walked, his gaze occasionally flickered towards Tanjirou. The memory of Yoriichi appeared once again in his mind and his irritation heightened. He despised the feeling whenever Yoriichi haunted his memories. He loathed the fact that Yoriichi's face was the only one he could never forget.

His father, his mother, the men who trained him... all their faces faded into oblivion, lost in the depth of his memory. His comrades, his wife and children... their faces vanished forever.

But not Yoriichi's.

Kokushibo knew that it was unjust to blame Tanjirou. The boy probably had no knowledge of Yoriichi or any connection to him. After all, Yoriichi's wife and their unborn child had passed on, and Yoriichi had never remarried. Yoriichi's bloodline ended with him. While it was possible for some of Kokushibo's descedants to still be alive, Kokushibo wasn't entirely sure, yet he was certain that Tanjirou wasn't a blood relative of Yoriichi.

Therefore, it would be unfair to hold him responsible for reminding Kokushibo of Yoriichi. However, Kokushibo wasn't able to null the slowly growing rage deep inside his cold heart.

As they continued their walk, the silence was broken by Tanjirou's soft inquiry. "Kokushibo-sensei?"

Kokushibo stopped, his stride ceasing as he turned to look at the boy. A brief moment of silence passed before he responded, his voice cool and controlled. "What is it..?"

"Are you angry?" Tanjirou asked with a curious headtilt.

The question caught Kokushibo off guard, but he quickly composed himself, his face maintaining its usual stoic expression. "Angry?" He echoed, a hint of surprise and a tiny bit of irritation in his voice. "What makes... you think... that?"

Did Tanjirou somehow sense his growing anger? How did the boy know?

Tanjirou seemed to shrink back at the irritated tone of Kokushibo's voice. "Your scent, it became angry..." The boy tried to explain.

Kokushibo's irritation faded into curiosity and surprise as Tanjirou explained that he sensed Kokushibo's anger through scent. A newly turned demon, barely an hour old, able to detect Kokushibo's anger by his scent alone? The boy had only been a demon for a tiny while, yet he was already displaying keen senses that even most fully developed demons would envy. Most demons in this state were still complitely feral, maybe able to have some proper thought if they had a strong mind.

"I-I really don't know how to explain it... You just smelled angry." Tanjirou mutters, sounding slightly embarrassed and ashamed.

Kokushibo listened to Tanjirou's explanation, his curiosity growing with each word. The boy seemed slightly embarrassed and ashamed as he admitted that he couldn't quite explain how he sensed the anger. Kokushibo's mind raced with various possibilities, trying to understand how the boy's heightened sense of smell worked.

"Hm.." He mused, his voice carrying a hint of surprise. "Your sense... of smell is... unusually keen... even for a demon."

Tanjirou raised his gaze from the ground to look up at Kokushibo before reverting his gaze back down. Such a skittish child... Just like how Yoriichi was when he was little...

Stop that.

"...Are you angry at me, sensei?" Tanjirou asked carefully.

"And if... I am?" Kokushibo responded, keeping his voice measured, revealing nothing.

"I... I'm sorry for whatever I did, sensei." Tanjirou apologised.

The boy's immediate apology caught Kokushibo off guard. Tanjirou's guilt was palpable, even though the younger demon had done nothing wrong.

Kokushibo let out a small huff, crossing his arms. "You don't... need to... apologise for... something you... haven't done." The Upper Rank's tone was stern... but not unkind. Deep down Michikatsu knew that he couldn't stay mad at the child infront of him.

"...I hope I'm not making it worse then..." Tanjirou mumbled. "I don't want to be a bother..."

"I hope I didn't make father more angry at you, brother." A distant voice said.

"Nonesense!" Another voice replied. "Come on, eat up. I managed to steal some mochi from the chefs."

"...You don't need to steal food to feed me, brother." The other one mumbled. "I don't want to be a bother..."

Kokushibo shook the memories off and forced himself to look at the boy infront of him. "You aren't... a bother." His tone was a tad bit softer now, though still very clearly stern. "...Never say that again."

"You're not a bother, Yoriichi. Never say something like that again, you hear me?"

There was a brief moment of hesitation before Tanjirou nodded in agreement. "Yes, sensei." Although the boy's tone was hesitant, Kokushibo realized that Tanjirou would keep his promise.

Kokushibo regarded the boy for a moment, his eyes studying him silently. Kokushibo was conflicted, struggling between seeing Tanjirou as his own person... or just a replica of Yoriichi...

...He doesn't know which one he'd prefer.

Kokushibo pushed the irrevelant thoughts from his mind. "Come on." He motioned for Tanjirou to follow. "We're almost... there."

Tanjirou, as before, simply nodded and followed after Kokushibo, though now his demeanor was noticeably less tense than before. The two demons continues their walk, the silence wasn't uncomfortable, but rather, comfortable. It was peaceful. The night was calm and quiet, the darkness surrounding them seemed endless.

After a while, they arrived at a relatively large clearing in the forest, surrounded by tall trees.

Tanjirou gave a curious and questionging glance in Kokushibo's direction, but just as Kokushibo expected, the boy said nothing and merely waited for Kokushibo to explain.

Then the sound of a biwa was heard in the otherwise empty forest, and shoji doors appeared from thin air, opening a way into the Infinity Castle. Kokushibo needed to inform Muzan about Tanjirou before doing anything else.

Kokushibo gestured towards the doors, indicating Tanjirou to follow him. "Come, and... stay close... to me."

Tanjirou nodded and followed Kokushibo into the Infinity Castle. The boy's eyes widened in awe as he took in the endless halls of the fortress, the labyrinthine structure stretching into eternity. Kokushibo led the way, navigating the convoluted layout had become like a second nature to the Upper Rank over the years.

Tanjirou on the other hand seemed to cling to Kokushibo's side, a mixture of nervousness and awe visible in his expression. The young demon seemed almost afraid to take even a single step away from the Upper Moon, as if he might get lost in the endless labyrinth. Michikatsu will never admit to how he might find the boy's clinginess amusing.

As they walked further into the maze-like halls, Kokushibo spotted a familiar figure: Nakime, the demon responsible for controlling the Infinity Castle.

"Nakime." He called out. The demoness looked up from her biwa, recognizing Kokushibo immediately.

"Upper One." She greeted.

"I need to... speak with... Lord Muzan." Kokushibo replied, his tone, as always, being calm yet firm.

"Understood." Nakime nodded and strummed her biwa, teleporting Kokushibo and Tanjirou into a different part of the castle, right behind a door. Behind that door was the demon king, aware of Kokushibo's arrival.

Kokushibo turned to look at Tanjirou, his gaze being serious. "Listen carefully, Tanjirou... Do not speak... unless you're spoken... to by him... I do not... want you... crossing any... boundaries or... disrespecting him. Do you... understand?"

Tanjirou nodded, shoving his nervousness down. "Yes, Kokushibo-sensei."

With a simple knock, and a "Come in." from the demon king, Kokushibo entered the room, with Tanjirou nervously following. Kokushibo kneeled, and Tanjirou did the same, having a hunch that it was better to do as Kokushibo was doing. Muzan did not turn his gaze from the book in his hands for a while. Then after what felt like ages, Muzan turned his attention to the two demons in the room.

"What is it, Kokushibo?"