Isekai Adventure in the Dimensional Cube

The Kamado family became the inheritors of the Breath of the Sun after Tsukiguni Yoriichi encountered Kibutsuji Muzan and let him escape.

At that time, because Tsukiguni Yoriichi let Kibutsuji Muzan and the demon Tamayo escape, and his close kin in the Ghost Hunter Corps killed the leader of the Corps, he faced blame and was expelled from the Ghost Hunters.

With nowhere to go in the Ghost Hunter Corps and having lost his identity as a Ghost Hunter, Tsukiguni Yoriichi, all alone in the world, came across an ancestor of the Kamado family who was under attack by demons.

Yoriichi saved him and they became good friends.

Two years later, Yoriichi visited this friend again, told him his story, and at his friend's request demonstrated the Breath of the Sun.

The Breath of the Sun that Yoriichi demonstrated then was thoroughly memorized by the Kamado family ancestor, who imprinted all of the movements into his heart.

Thus, the Dance of the Fire God was born within the Kamado family.

Upon parting, Yoriichi also gifted his own Sun Wheel Earrings to the Kamado family ancestor.

From then on, Yoriichi was no longer seen and never met with the Kamado family ancestor again for the rest of his life.

However, the Breath of the Sun that Yoriichi personally demonstrated was handed down within the Kamado family, along with the Sun Wheel Earrings.

Therefore, although the Kamado family was an ordinary family that sold charcoal from generation to generation, they were also the sole inheritors of the Breath of the Sun in this world.

Otherwise, why would Tanjirou's father understand the Transparent World?

It was precisely because he had learned the Breath of the Sun from a young age that he unintentionally mastered the Transparent World.

Unfortunately, Tanjirou's father had poor health and had been bedridden for many years; he had passed away from illness three years ago. Otherwise, with his natural talent for learning the Transparent World without a master, if he had joined the Ghost Hunters and formally practiced swordsmanship, he would surely have been a swordsman even stronger than Himejima Gyoumei, the strongest pillar of the Corps.

"So that's how it is..."

After listening to Reiger's explanation, Tanjirou was stunned for quite a while and had not come back to his senses.

It couldn't be helped.

A humble charcoal-selling family suddenly turning into the powerful progenitor of Breath techniques — the impact was just like finding out "I'm actually a wealthy heir."

"Ding-a-ling—"

Appropriately, a wind blew by, making the earrings on Tanjirou's ears sway gently, ringing like wind chimes.

The pleasant sound not only made Reiger feel nostalgic, but it also awakened Tanjirou.

"This must be fate, right?"

Tanjirou clenched his fists, a resolute emotion appearing in his eyes.

As the founder of the Breath of the Sun, Yoriichi was unable to kill Kibutsuji Muzan, which led to his encounter with Tanjirou's ancestor, and fortuitously, the Breath of the Sun, also known as the Dance of the Fire God, was passed down.

And as inheritors of the Breath of the Sun, the Kamado family was almost wiped out by Kibutsuji Muzan, leaving only him and his sister, who had been turned into a demon.

Tanjirou wanted to turn his sister back into a human, so he had been seeking Kibutsuji Muzan to find a way to revert demons back into humans.

With all factors combined, Tanjirou indeed felt the hand of fate.

He must defeat Kibutsuji Muzan.

Whether it was to fulfill Yoriichi's regret as an inheritor of the Breath of the Sun, or as the eldest son of the Kamado family seeking revenge and a way to restore his sister, Tanjirou felt he had to defeat that man.

Reiger, observing Tanjirou's steadfast gaze, suddenly spoke.

"If you want your sister to become human again, perhaps I can help you."

Such unexpected words completely stunned Tanjirou.

"What... what...?"

Tanjirou couldn't believe his own ears.

But Reiger had indeed said it.

"I can help turn your sister back into a human."

Reiger's casually spoken words threw Tanjirou into unprecedented excitement.

"Really... Is that true, Mr. Yoriichi!?"

Tanjirou couldn't help but grab Reiger's clothes.

"Really."

Reiger was not speaking thoughtlessly.

"People become demons solely because Kibutsuji Muzan injects his own blood into their bodies, altering their nature," Reiger explained. "Therefore, theoretically speaking, if the blood of Kibutsuji Muzan within a demon's body can be broken down, it should be possible to turn them back into humans."

To grow stronger, demons relied on consuming humans, but they could also increase their power with the blood of Kibutsuji Muzan.

The more blood Kibutsuji Muzan shared with a demon, the stronger that demon became.

Although the power in the blood could be so intense that weaker demons couldn't withstand it and would explode, conversely, as long as the demon could endure it, they could become much stronger than the Upper Moon One, Kokushibou, by relying on Kibutsuji Muzan's blood.

Thus, it was clear that Kibutsuji Muzan's blood was the source of a demon's power.

Thereby, if that part of the demon's blood could be broken down and the demon's power completely erased, then wouldn't the demon turn back into a human?

For Reiger, with the power to break down magic, this was entirely doable.

"Mr. Yoriichi... I... I...!"

Tanjirou became so agitated that he was incoherent with emotion, and even tears flowed down his face.

"Don't look at me like that; I simply don't want your sister to get into trouble because of me," Reiger patted Tanjirou's shoulder and said, "Later, I expect I'll personally kill Kibutsuji Muzan, and once Kibutsuji Muzan is dead, all the demons in the world will disappear along with him. If your sister dies because of this, my sin would be too great."

The original work did not particularly address the fate of the world's demons after the death of Kibutsuji Muzan.

Whether they all died with him or turned back into humans, Reiger wasn't sure either.

If it was the latter, that would be better, but if it was the former, then Tanjirou would have to face separation from his only remaining close kin in life and death.

Therefore, remembering this, Reiger had planned to take the opportunity to do a good deed and save Tanjirou's sister.

"Thank you! Mr. Tsukiguni! Thank you!"

Tanjirou kept bowing to Reiger and thanking him, tears streaming down his face, crying unsightly.

"Let's go," Reiger smiled, and said, "Take me to meet your sister."

"Yes!"

Tanjirou responded loudly.

......

The dwelling where Tanjirou lived was a communal dormitory provided by the swordsmith village for ordinary Demon Slaying Corps members.

Some dormitories were large, others small; some could only accommodate two or three people, while others could house about ten people. These buildings were located on the outskirts of the village and were evidently just recently constructed.

Tanjirou lived in a smaller dormitory that could only house three or four people. Thus, in the swordsmith village, he lived with Zenitsu and Inosuke, and his sister Nezuko was also placed there.

Under Tanjirou's guidance, Reiger arrived there to see his sister, who had always been kept in a wooden box.

She was a girl who looked about 14 years old, not much different in appearance from Mistis.

The girl had long, black hair that reached her waist, was dressed in a pink kimono with black Haori, and had a bamboo tube in her mouth. She was cute with the potential to be a beauty.

At that moment, the girl was sleeping deeply, wrapped in blankets on top of the tatami mat.

I'm back, Nezuko.

Kneeling by the blankets, Tanjirou reached out his hand, gently touched his sister's head, and exhibited a kind and gentle expression Reiger had never seen before.

"Is she asleep?" Reiger observed Nezuko.

"Yes," Tanjirou said, his voice unconsciously lowered as he said, "Ever since she became a demon, Nezuko often sleeps like this, using most of her time to sleep. It seems she's maintaining her strength through sleep and suppressing her demon instincts to avoid eating humans."

Here, it must be said, Tanjirou's sister was indeed extraordinary.

Others, upon becoming demons, were usually controlled by uncontrollable violent instincts, attacking and feasting on humans, losing not only their humanity but also the memories from their time as humans.

Nezuko was the only demon who overcame the instinct to eat humans through sheer will, retaining some of her humanity at the call of Tanjirou.

She was the only demon in the world who had never eaten a human, and because of her, the Demon Slaying Corps had even experienced internal strife.

In the Demon Slaying Corps, associating with demons or defending man-eating demons was taboo.

Even Tsukiguni Yoriichi, as strong as he was, was chastised by the Demon Slaying Corps for once sparing Tamayo, let alone Tanjirou, who was considered an "average" member.

Therefore, the Demon Slaying Corps wanted to execute his sister, and he almost faced execution himself. Had it not been for the Water Pillar Tomioka Giyuu vouching for him and the Insect Pillar Kochou Shinobu also taking actions in favor of Tanjirou afterward, coupled with the main family head Ubuyashiki Kagaya understanding the situation with Nezuko and permitting her existence, Tanjirou and Nezuko might no longer have been part of the Demon Slaying Corps.

Even so, most members of the Demon Slaying Corps still did not recognize Nezuko, and they were even unwilling to recognize Tanjirou who walked with demons, even if Nezuko proved that she would not eat humans in the last Pillar meeting.

Fortunately, there were now quite a few Pillars who acknowledged Tanjirou.

The Flame Pillar Rengoku Kyoujurou became Tanjirou's master, so naturally, he recognized Nezuko.

The Love Pillar Kanroji Mitsuri never had much prejudice against Tanjirou and was quite approving of both Tanjirou and Nezuko, being a kind person herself.

The Mist Pillar Tokitou Muichirou seemed indifferent to the existence of Tanjirou and Nezuko, hence chose to ignore them.

The Stone Pillar Himejima Gyoumei appeared to be in a wait-and-see state, his intentions unclear.

As for the Sound Pillar Uzui Tengen, he could not exactly be said to have acknowledged Tanjirou and Nezuko, but he had also stopped advocating for eradicating them altogether.

Only the Wind Pillar Shinazugawa Sanemi and the Serpent Pillar Iguro Obanai, the two with the worst temperament, personality, and popularity in the Demon Slaying Corps, were still displeased with Tanjirou till now.

And as someone who knew the original story, Reiger's view of Nezuko was naturally one of approval.

His coming here in the first place was proof of that.

"I'm going to start now," Reiger knelt on one knee, placing his hand on Nezuko's forehead.

"Please... please do..." Tanjirou bowed deeply to Reiger, his face full of nervousness.

Reiger paid no more attention to Tanjirou and directly released the disintegration magic.

"Hum…"

A red ripple suddenly appeared.