Improving the System

As he expected, while walking through the bustling market, Muzan was stopped by a voice filled with surprise:

"Doctor?!"

Muzan turned his head to look to his side, and a figure showing signs of age stared at him in stunned surprise.

Tears welled up in his eyes, and he seemed a bit lost.

"Haganezuka?"

Muzan asked tentatively.

The aged figure was wearing gray-brown clothes, and his black hair, streaked with gray, still maintained the familiar hairstyle.

"It really is you!"

Haganezuka, filled with surprise, weaved through the crowd and hurried over.

Muzan took Haganezuka to a restaurant, poured him some tea, and said with a smile:

"I've been looking for you for quite some time."

Haganezuka, who was already over forty, smiled like a child in front of Muzan, who looked only twenty.

"I want to repay your kindness while I'm still alive."

As soon as Haganezuka finished speaking, hurried footsteps suddenly echoed from outside. The footsteps approached rapidly, and in the blink of an eye, three people wielding swords burst into the restaurant.

"Demon!"

"Get away from here! He's a demon!"

The demon slayer shouted, charging with his sword.

Muzan's mood was immediately dampened. He looked at Haganezuka beside him.

When he saw the doctor, who looked exactly the same as he did back then, he had already made a guess.

Now, watching the panicked crowd flee, yet the doctor showed no fear on his face as the demon slayer swung his sword at Muzan, he was certain.

A demon slayer grabbed his wrist, trying to pull Haganezuka away, and shouted, "This guy is a demon! Run!"

Muzan stood up, blocking the Nichirin Blade with one hand. He looked at Haganezuka, whose wrist was being held, and who showed no fear and refused to leave. Muzan's mood instantly improved, and he smiled.

"Do you want to become a demon?"

Haganezuka nodded firmly.

Seeing this, the demon slayer, though unsure of the exact situation, could clearly tell that this person wanted to become a demon!

Without hesitation, he raised his sword and swung it directly at both of them.

Demon Annihilation!

Muzan grabbed the Nichirin Blade and applied sudden force.

Crack!

The sturdy Nichirin Blade snapped in two.

Then, he kicked them away one by one: "Stop causing trouble."

He withdrew his gaze, his fingernails growing long, and with Haganezuka looking slightly nervous, he thrust a fingernail in.

Before becoming a demon, Haganezuka never imagined that becoming a demon would be so painful!

And why did he have to stab him in the head!

The three demon slayers watched in stunned silence as a demon was born. However, they were kicked in the abdomen and were in too much pain to get up, glaring fiercely at Muzan.

Seeing this, how could they not realize that this person was the Demon King, Muzan Kibutsuji!

Haganezuka, who had regained his youthful appearance, also seemed to have regained his youthful spirit. He came to the Infinity Castle with Muzan and looked around curiously.

"From now on, your name will be Akaza. Consider it a farewell to your past self."

Akaza nodded: "Okay."

Muzan added, "As a demon, I won't make you work yourself to death, but I have one condition!"

Hearing this, Akaza's expression turned serious. He listened carefully to what Muzan would demand, determined to fulfill it completely!

"You must learn to read all the characters!"

Akaza: "???"

What did you say???

"Alright, I'll send you to Kokushibo first. Learn from him."

Kokushibo: He's really giving me work to do! I still need to train!

From that day on, Akaza began his arduous learning journey. Kokushibo was unwilling to take much responsibility, simply throwing books at him and rarely checking in, only occasionally coming by to deal with accumulated problems.

Akaza: I want to cry.

Who knew becoming a demon required literacy?!

After several years, Akaza finally passed Muzan's test.

It was excruciating.

He had thought becoming a demon meant serving Muzan, that he'd do anything without hesitation.

After all, Muzan, even as the Demon King, had given him a great impression. He believed Muzan wouldn't do anything evil and was determined to repay him with his infinite life.

But he never expected the first step of repayment to be learning to read!

He could fight, brawl, or even kill!

He'd honed himself his whole life, only for Muzan to send him back to school.

He could just cry.

However, he hadn't just spent these past few years learning to read. He had also mastered his Blood Demon Art, Destructive Death, strengthened his resolve to become stronger, and learned some of the strange "rules" among demons.

For example, Muzan liked being called "Boss," though "Lord Muzan" was also acceptable.

Muzan liked poking heads.

Demons weren't afraid of the sun, so go ahead and bask in it!

Not eating people was fine, just eat properly.

Demons who were somehow not controlled by Muzan – Half-Demons – kill them on sight!

Things like that.

Soon, all demons received a notification from Muzan.

Muzan established some systems. While they weren't very useful, at most, those with special titles would be granted the right to create demons by Muzan. Other than that, it was just a title, but it did stir up the demons' competitive spirit.

The first was the Twelve Kizuki.

Divided into Upper Ranks and Lower Ranks.

Six in each.

Kokushibo ascended to Upper Rank One, Akaza to Upper Rank Two. The rest could come to the Infinity Castle to apply.

Once one became a Twelve Kizuki, they could be challenged at any time, initiating a bloody battle for their position.

The loser would be replaced.

And Tsugikuni Yoriichi was given the title "Heavenly Flower."

Tsugikuni Yoriichi: "Does Muzan have a screw loose?"

He also established Star Ranks, specifically for powerful support personnel.

Tamayo, Nakime, Yanagisawa Noriyuki, Maruoka Kinuko, and Maruoka Gōnin were given the title of Star Rank.

In truth, Tsugikuni Yoriichi, Kokushibo, Tamayo, and the others didn't want to play along with Muzan's games, but they still gave him some face.

Muzan: "Well, I guess I should thank you then!"

In short, with this, the system among demons was perfected.

However, considering Tamayo and Yanagisawa Noriyuki were still busy tinkering with Wisteria Flowers, and others had their own affairs, Muzan didn't make a big fuss about summoning all the "listed personnel" to the Infinity Castle for a pointless assembly.

Infinity Castle.

Muzan pointed at Akaza, who had passed the cultural exam, and lectured Kagetsuki Chiyo, who refused to study no matter what:

"Look at him! He learned to read in just a few years! How can you, a demon hundreds of years old, not give me some peace of mind!"

Kagetsuki Chiyo looked like a student being scolded by a teacher, lowering his head and remaining silent.

Muzan could tell from his demeanor that he knew he was wrong but would never change.

So, he decided not to waste any more time.

He looked at Akaza: "I'm leaving him to you. Teach him to read."

He glared at Kagetsuki Chiyo again: "If you don't learn to read, don't even think about leaving the Infinity Castle!"

"Nakime, if he uses his Blood Demon Art, give him a good thrashing!"

Nakime nodded.

After giving the orders, Muzan left the Infinity Castle.

Akaza and Kagetsuki Chiyo were left looking at each other.

Akaza was dumbfounded. He had finally managed to learn to read after years of hard work, and now he had to go through the trouble of teaching someone else???

"Heh heh..."

Kagetsuki Chiyo, the "bad student," scratched his head and looked sheepishly at Akaza.