Isekai Adventure in the Dimensional Cube

In Reiger's view, Tsukiguni Yoriichi was undoubtedly the pinnacle of combat ability in this world.

Not only because he created the breathing techniques and brought them to the people of this world, but also because his natural talent was truly superhuman.

He was born with an innate understanding of the principles of the breathing techniques, and the Sun Breathing technique was something he created after organizing these principles.

He was even born with cheats; not only did he have a pattern on his forehead that greatly enhanced his physical abilities, but he also naturally possessed the "Supreme Domain" that Akaza once mentioned, displaying extraordinary strength from childhood.

He also had an experience where he nearly eradicated the source of all ghosts, slaying the Ghost King who had survived for a millennium, causing the Ghost King to develop a psychological shadow. The Ghost King hid himself, unwilling to appear in this world until his death.

All these deeds made Reiger feel from the bottom of his heart that Tsukiguni Yoriichi, a swordsman born in the Warring States period, was the most bug-like existence in this world.

Unfortunately, when he was most likely to resolve everything and end the tragedy that had lasted for a thousand years, he failed.

That failure caused this naturally cheat-possessed swordsman to fall from grace, not only was he expelled by the Demon Slayer Corps, but he also left behind lifelong regrets that he could never let go.

Because of him, the Demon Slayer Corps faced several major crises of destruction.

Fearing Tsukiguni Yoriichi, fearing the Sun Breathing, that Ghost King, after surviving the crises brought by this bug-like genius swordsman, started to hunt down everyone who knew about Sun Breathing, almost disintegrating the Demon Slayer Corps several times.

Thus, the legacy about Tsukiguni Yoriichi and Sun Breathing was severed, with only the Ubuyashiki Family, who had always headed the Demon Slayer Corps, retaining some records.

However, Ubuyashiki Kagaya also said this.

"The Rengoku Family should also have retained some records."

Ubuyashiki Kagaya suddenly brought up this matter to Rengoku Kyoujurou in the courtyard.

"The Rengoku Family?"

The pillars all looked towards Rengoku Kyoujurou at the same time.

"Our family?"

Rengoku Kyoujurou was also somewhat stunned.

"Yes." Ubuyashiki Kagaya nodded and said, "The Flame Pillar of the Demon Slayer Corps has almost always been held by a member of the Rengoku Family, thus, the Rengoku Family is a long-standing Ghost Hunter lineage."

"Originally, it was the ancestors of the Rengoku Family who encountered Tsukiguni Yoriichi, introduced him and Sun Breathing to the Demon Slayer Corps, which led the Demon Slayer Corps to be what it is today. Tsukiguni Yoriichi often interacted with the Rengoku Family while he was teaching the breathing methods, and even after being expelled from the Demon Slayer Corps, he still maintained contact with the Rengoku Family."

"Therefore, the Rengoku Family should have records like the Ubuyashiki Family, the proof of which is that the Flame Breathing of the Rengoku Family is perhaps the closest breathing style to Sun Breathing among all the breathing methods."

Sun Breathing and Flame Breathing are indeed very similar.

Both are sword techniques manipulating fierce flames, experts in handling fire.

But Sun Breathing is not merely a power of fire; it is the power of the sun.

From this point of view, Flame Breathing might be considered an inferior version of Sun Breathing.

Of course, the five fundamental breathing techniques all derived from Sun Breathing; they could all be considered inferior versions of Sun Breathing.

As for Sound Breathing, Snake Breathing, Mist Breathing, Love Breathing, and Insect Breathing, they are modified versions among the inferior versions, and probably only a few pillars present could play with these styles.

"Kyoujurou, you are not very fond of researching this history, are you? When you have free time, your research is also sword techniques, so you are unaware of it, right?" Ubuyashiki Kagaya said smilingly to Rengoku Kyoujurou, "Your father might be more familiar with these secrets, if you're interested, perhaps you could ask him."

Upon hearing this, Rengoku Kyoujurou fell silent.

"Anyway, the resurrection of the strongest breathing technique is a good thing." Ubuyashiki Kagaya turned to the pillars and said, "You must also not disrespect the swordsman who has inherited the great ancestor's name and techniques, understand?"

"...Yes."

The pillars bowed their heads and remained silent for a while before responding.

Even the most uncontrollable Shinazugawa Sanemi and Iguro Obanai were not speaking against it at this moment.

But what they really thought about it was known only to themselves.

Watching all this, Reiger's regard for Ubuyashiki Kagaya rose even higher.

Not because he spoke on his behalf, but after explaining the origins and implications, Ubuyashiki Kagaya had no intention of investigating some matters regarding Reiger.

For example, why was he able to use the long-lost Sun Breathing?

Or, why did he know about the existence of Tsukiguni Yoriichi despite the severed inheritance, and use his name?

Ubuyashiki Kagaya didn't ask any of these.

He hadn't even inquired about Reiger's origins; bringing him here to meet was an act of trust in itself.

This alone made Reiger hold the Family Head of the Ubuyashiki family in much higher esteem.

"Tsukiguni Yoriichi." Ubuyashiki Kagaya asked Reiger, "Would you be willing to stay in the Demon Slayer Corps?"

This question made all the pillars present inevitably look at Reiger.

Though some were not very fond of Reiger, at least, they recognized his strength.

Being able to effortlessly defeat three pillars, his strength was beyond doubt, and slaying an Upper Rank was no empty talk.

Furthermore, with his mastery of the strongest breathing technique, if he could stay in the Demon Slayer Corps, the Corps' strength would definitely become unprecedentedly strong.

If this could help the Sun Breathing be preserved within the Demon Slayer Corps, that would be even better.

But Reiger did not agree.

"To tell the truth, I'm not very keen on staying in the Ghost Hunter team." Reiger said, "I might need time to study some secret techniques and engage in solitary training next. If I stay in the Ghost Hunter team, I doubt I will have such leisure time."

Reiger wasn't particularly averse to joining the Ghost Hunter team.

By joining the Ghost Hunter team, Reiger could use their intelligence network to know where the ghosts were and thus gain experience.

But as he had imagined before undergoing Dimensional Travel, the ghosts in this world weren't numerous enough to warrant mass extermination. Each ghost-killing expedition involved traveling to various towns, consuming a significant amount of time, and he could only kill about one ghost at a time, making the efficiency of gaining experience painfully low.

If those ghosts were powerful, that would be another story.

The stronger the enemy, the more experience he would gain. If the adversary was strong enough, it wouldn't be a waste of time for Reiger to undertake trip after trip.

The problem was, he had figured out that even the highest-ranking ghosts were only equivalent to Level 4 elites, which, given Reiger's current level, wouldn't significantly increase his experience.

Unless the Ghost Lord appeared, or the strongest of the twelve ghost moons made his move, then Reiger might show some interest.

As he knew, in the original story, these two were far superior to all the other ghosts in the twelve ghost moons, potentially possessing strength equivalent to Level 5.

Especially the Ghost Lord—if there was anyone in this world that could be a match for Reiger, it might only be him.

If he encountered these two ghosts, Reiger would have an interest in acting, but for the rest, he felt it was better, instead of coveting those little bits of experience, to collect some of this world's breathing techniques to see if he could accomplish his idea.

If he could, then this trip through Dimensional Travel would be considered worthwhile.

Hence, Reiger dispelled the idea of joining the Ghost Hunter team.

Once joined the Ghost Hunter team, it was clear they wouldn't allow him to casually stay at home to train. They would inevitably assign him numerous tasks to hunt ghosts.

Considering this, Reiger tactfully declined Ubuyashiki Kagaya's invitation.

However, Ubuyashiki Kagaya was not disappointed; rather, he was quite interested in Reiger's words.

"Solitary training to study secret techniques, huh." Ubuyashiki Kagaya smiled gently, "Is there anything I can help you with?"

"Really?" Reiger asked in surprise.

"Yes," Ubuyashiki Kagaya nodded, "Even if you don't join the Ghost Hunter team, as long as there are people in this world who can kill ghosts, people who can threaten the upper moons, or even the Ghost Progenitor, it is meaningful to us."

"Is that so?" Reiger looked straight at Ubuyashiki Kagaya and said, "What if what I want are the breathing techniques?"

These words seemed to catch Ubuyashiki Kagaya off guard.

But he did not hesitate.

"As long as it helps you, then naturally, it's no problem."

Ubuyashiki Kagaya agreed promptly.

The inheritance of breathing techniques was not exactly a secret; the Ghost Hunter team even had specialists teaching others breathing techniques outside, helping to bring new blood into the team.

It can be said that as long as one has the right connections and intent, the Ghost Hunter team generally welcomes those who want to learn the breathing techniques.

"Which breathing technique do you need?"

Ubuyashiki Kagaya asked Reiger.

"The five fundamental breathing techniques of wind, flame, water, rock, and thunder, I will probably need them all," Reiger thought for a moment, then added, "I'm not sure if the other derivative breathing techniques can be useful, we'll see if I need them later."

Reiger's remark instantly offended quite a few people.

"Hmph, my Sound Breathing is quite elegant."

Uzui Tengen snorted coldly.

"Looking down on our breathing techniques, huh?"

Iguro Obanai became even more displeased.

"Oh dear, we're being underestimated."

Kochou Shinobu, on the other hand, had a smiling face.

"Oh oh, I'm sorry to not know if they can be useful."

Kanroji Mitsuri puffed up her cheeks.

"......"

Tokitou Muichirou remained silent, as if lost in thought.

"Rengoku," Ubuyashiki Kagaya then instructed Rengoku Kyoujurou, "Let Tsukiguni Yoriichi stay at your place for now. Remember to treat him well."

"Yes, Family Head!" Rengoku Kyoujurou naturally had no objections.

"Well, that's it for today," Ubuyashiki Kagaya suddenly smiled, "I hope to see everyone gathered here again next time. Don't let anyone be absent."

"Yes!"

All the pillars bowed their heads.