Naruto: I'm really not an evil scientist!

As for whether Rui would be killed by the Demon Slayer Corps due to his high-profile actions, Muzan didn't care at all. If Rui hadn't found Tamayo before he died, Muzan would even have cursed Rui as a piece of trash.

As long as it increases the probability of finding Tamayo to heal oneself, it doesn't matter how many ghosts die.

In Muzan's mind, all demons were nothing more than tools to keep him alive, and their so-called favor and trust were nothing more than a pretense for exploitation.

Muzan is nothing more than a beast whose DNA is etched with the instinct for survival; he will stop at nothing to survive.

Inside Mount Natagumo, a short, sickly-white demon named Rui muttered angrily, "Unauthorized escape is unforgivable!"

His eyes flashed with madness and cruelty. The weak "family members" beside him trembled as they watched the enraged Lei, trying to huddle together and not want this mentally twisted freak to notice them.

Just as Muzan had expected, Rui was furious upon receiving the news that Tamayo, the traitor who had broken the family bond and escaped, had been captured. Without waiting for Muzan's urging, he spontaneously ordered the demons to go out of the mountains with him to search for Tamayo.

……

One week later, within the Demon Slayer Corps.

Kagaya Ubuyashiki is undergoing training with Master Hiruko No. 1 alongside Flame Pillar Kyojuro Rengoku.

Master Hiruko No. 1 is Hiruko's capable assistant, a scientific research ninja. Although not a ninja, he has mastered extraordinary skills, especially in integrating scientific research concepts into martial arts training.

After undergoing various training exercises, including a 30-lap run around the mountain, a brisk walk on water, hand-carving rocks, and waterfall meditation, the two of them were taken by the No. 1 of the Hiruko to rest in the open space in front of the Butterfly House.

"Master Hiruko No. 1, I... I can continue!" Kagaya Ubuyashiki said, panting heavily. He had finally shaken off his frail health and wanted to cherish every minute and second to become stronger.

"Yes! Me too!" Rengoku Kyojuro patted his chest with great confidence, appearing more at ease than Ubuyashiki Kagaya.

"Cultivation should be done in moderation. If you push yourself too hard and injure your body, then you will lose more than you gain."

Hiruko No. 1 said with a smile, then his expression turned serious, "Moreover, today I will teach you two powerful secret techniques that can only be used in extremely dangerous situations."

"Secret technique?"

Kagaya Ubuyashiki perked up. He knew his own situation best. With his current strength, he really couldn't beat Muzan without using some kind of cheat code. After all, he had only gotten rid of his illness and weakness, and there was still a big gap between him and a Pillar-level swordsman.

"That's right! The first secret technique I'm going to teach you is the Seven-Day Breathing Technique. The principle of this breathing technique is similar to yours; both involve activating the whole body by absorbing a large amount of oxygen."

Hiruko No. 1 cut to the chase, saying, "This technique was created by Lord Hiruko based on scientific principles and combined with breathing techniques. Once this move is used, it can greatly increase chakra levels and physical attributes through physical activation, and can also instantly multiply one's lung capacity."

"Instantly increases lung capacity! Really?" Rengoku Kyojuro's eyes lit up.

Although having chakra allows one to switch to internal breathing if they cultivate Sage Mode, these Pillars did not cultivate Sage Mode and relied on their original breathing techniques. To become stronger through breathing techniques, one's lung capacity is a crucial factor.

Being able to instantly increase lung capacity means being able to instantly increase one's combat effectiveness.

For them, it would be quite difficult to create their own internal energy technique like Hiruko, who, after learning the Sage Breathing Technique, instantly created it by combining it with chakra. This technique uses chakra to circulate within the body and simulate the original effect of the breathing method.

So far, only the Mist Hashira, Muichiro Tokito, has achieved this, creating his own unique internal energy by combining his self-created Mist Breathing with chakra.

The other pillars are also geniuses among humans. Although they have not been able to successfully develop them, they have all made some progress and will be able to develop their own internal cultivation techniques in a few weeks.

However, since they failed to learn the Yin Sealing Technique, they were unable to accumulate chakra, nor did they possess the "Qi Sea Dantian" superpower organ that humans in the martial arts world have. They could only continuously temper their physical bodies in the process, enhance their physical qualities, and develop new chakra properties and form transformations accordingly.

"That's right. When you use the Seven-Day Breathing Technique, it won't completely disrupt your original breathing rhythm. Instead, it will instantly and exponentially increase the user's lung capacity, allowing the user to inhale a large amount of oxygen, thus activating the body, making the chakra in the body more active and violent, and exponentially increasing combat power."

Hiruko No. 1 said solemnly, "This is an extremely dangerous secret technique. Although the Seven-Day Breathing Technique has been modified by my god and is divided into nine levels, each level can double the lung capacity, and there are also corresponding methods for utilizing chakra and oxygen to maximize the activation of the body, I will only teach you the first three levels now."

"Why... I know, the human body has its limits." Kagaya Ubuyashiki was about to ask why, but he quickly figured out the reason himself.

The human body has its limits. Instantly increasing lung capacity several times over does not mean that the strength of the human lungs can keep up. Using the first few levels of the secret technique in moderation may have the effect of training the lungs, but if you directly open the ninth level, it will probably cause the user's lungs to explode and the body to collapse instantly.

Moreover, this might be a secret technique where the higher the lung capacity, the lower the level of safe use, since the flesh and blood of ordinary humans have limits, and the lungs cannot be strengthened indefinitely.

"That's right. The human body is fragile. The last few layers are not something that ordinary humans can use. Forcibly activating the ninth level is tantamount to suicide."

You are not the Pillar Men, such a terrifying inhuman race; learning the first three levels is enough.

In the third active state, you will have four times your normal lung capacity and a massive amount of chakra. For those of you who practice breathing techniques, the boost might be even greater, which is enough to deal with powerful enemies.

Beiliuhu No. 1 nodded.

Although the secret manuals taught by the Supreme God are all very powerful, many cannot be copied and practiced directly. They must be fine-tuned according to one's own situation or obtained through the Supreme God's grace. If one insists on practicing them regardless of everything, death is certain. These are all bloody lessons in his world.

"What's the name of that other secret technique, Master Hiruko No. 1?" Rengoku Kyojuro asked curiously.

"The Eight Gates Formation is a forbidden technique, a forbidden technique that can instantly burn away everything a mortal possesses, briefly allowing them to reach the pinnacle of spiritual transcendence and gain the qualification to throw a punch at a god."

Hiruko No. 1 said in a deep voice, "This technique was also created by Lord Hiruko. He knew that the human body has unlimited potential, so he created this technique to stimulate the limits of the human body."

The Infinite City was littered with corpses, and there were still severed limbs everywhere. Blood was splattered on the tatami mats, and it would not be an exaggeration to say that the blood flowed like a river.

A man who had returned from hell was wielding a wood-chopping axe, slowly slaughtering man-eating demons as he walked toward the Demon King.

To truly kill a demon, one must sever its neck with a Nichirin Blade? For this man, such a troublesome method is completely unnecessary.

As the inheritor of the Breath of the Sun, and with Hiruko's modified "hanging wall," Tanjuro Kamado can easily create wounds that even demons cannot heal. Therefore, like slaying a bear with an axe in the snowy night, he can easily kill demons.

Chapter 410

Kagaya Ubuyashiki is still training hard, while Tanjuro Kamado has already started his Musou attack in the Infinite Castle.

However, to Tanjuro's surprise, he didn't seem to encounter any powerful demons in the Infinity Castle. He didn't seem to have seen any of the so-called Twelve Demon Moons, and they were already close to the boss, Muzan.

He was unaware that Muzan, due to his illness, did not want powerful demons to see him in his weakened state. Therefore, in the Infinity Castle, Muzan only had some weak demons who had recently been transformed, besides Nakime as his attendant.

"That earring... who exactly are you?!" Upon seeing the earring hanging on Tanjuro Kamado's ear, Muzan Kibutsuji couldn't help but think of that god-like man, and his body trembled involuntarily. This was a symptom of Yoriichi Tsugikuni's PTSD.

"I am just an ordinary charcoal seller. I have come here specifically for revenge," Kamado Tanjuro said calmly, casually wiping the bloodstains off his axe blade. "I have come to seek justice for my family members who died because of you."

"You people are so annoying! It's the same old revenge rhetoric, nothing new."

Muzan roared in frustration, "At least you survived, that's enough! So what if your family was killed? Just be content with your luck and keep living your life as usual, isn't that better?"

Muzan kept hypnotizing himself, saying that there was only one Yoriichi Tsugikuni, and there would never be another Yoriichi Tsugikuni. This human could not possibly be as strong as Yoriichi Tsugikuni.

"Just consider those I killed as having suffered a great calamity; there's no need to delve into anything else."

"Gales, torrential rains, volcanic eruptions, earthquakes—no matter how many lives these natural phenomena claim, no one will attempt to seek revenge against natural disasters." While spouting what he considered self-evident statements, Muzan frantically called for the Twelve Demon Moons to come to his aid.

Muzan had no intention of fighting to the death. When he saw the familiar earrings, he already had the thought of retreating. He wanted the Twelve Demon Moons to cover his retreat.

"What did you say?" Kamado Tanjuro's eyes widened.

"People can't come back to life after they're dead. Don't dwell on things that can't be undone. Just focus on making money and living a peaceful life. That should be enough."

Most people are like that, so why can't you...?

"Third activation." As Kamado Tanjuro's cold voice fell, a massive gust of air rushed from the corner of his mouth into his lungs, and a golden-red flame suddenly rose from his body.

This is a unique technique he created by combining the Seven-Day Breathing Method with his own Sun Breathing, making it even more powerful than before.

Immediately afterwards, a magnificent and dazzling axe light flashed, and Muzan Kibutsuji's head fell to the ground.

Muzan's head was flying in mid-air, and now he finally realized the seriousness of the problem.

However, he has five brains and seven hearts, and as the progenitor of demons, Muzan has long since broken the limitation that ordinary demons would die if their heads were cut off by a Nichirin Blade. Cutting off one head is not enough to completely kill Muzan, so he can continue to live.

Of course, this is not because he has any extraordinary talent, or because Muzan has an extremely high talent in terms of the will to survive. When it comes to the desire to live, Muzan Kibutsuji is even more tenacious than a cockroach.

He was able to break through the limitations simply because he was afraid of death enough. The stronger a demon is, the stronger its will to survive is, and the more likely it is to break through its original limitations.

"Nakome! What are you doing, Nakome?!" Muzan's head roared angrily in mid-air, fear completely taking over his mind.

Tanjuro Kamado remained indifferent as he manipulated the crimson axe blade, which traced dazzling light across Muzan's body. In the blink of an eye, Tanjuro swung the blade over a thousand times, slicing away Muzan's rotten flesh and broken bones piece by piece, as if subjecting him to a slow, agonizing death.

Moreover, each axe strike contained immense destructive power, as if imbued with Tanjuro's rage, intent on burning Muzan Kibutsuji's flesh and blood cells to ashes.

Having mastered the techniques of the Transparent World, Tanjuro was naturally very familiar with Muzan's peculiar structure. He was also well aware of the regenerative abilities of demons, and in order to prevent Muzan from being resurrected in the future, he wanted to completely annihilate this evil demon king into dust and mince him into charred pieces.

*Tap!* The pipa string was plucked, and the inhuman, fleshy Muzan Kibutsuji was instantly teleported to another room.

"Why are you so slow? Are you trying to kill me? You piece of trash!" A twisted sound came from the piece of flesh, which even grew hands and feet that frantically lashed at Nakime, who was holding a biwa, as if it wanted to vent all the fear in its heart.

"I...I'm sorry, Lord Muzan." Nakime silently endured Muzan's punches and kicks, not daring to argue. She knew Muzan's despicable nature all too well, and she had become numb to it over the centuries.

The more you try to explain, the more tyrannical Muzan becomes. If you don't do what he wants, you'll be forcibly dismissed. In short, everything is their fault. Don't try to explain or flatter him; just accept it passively.

"Quickly summon the Twelve Demon Moons to hold that guy back!"

Muzan roared in frustration, "You're so slow, dawdling like a madman!"

"Found it." Kamado Tanjuro's voice came from behind him, as cold and ruthless as the Grim Reaper.

Muzan froze, then instantly shrank behind Nakime, grabbing her neck with his tentacles and yelling furiously, "Nakime, you bastard, have you betrayed me? How dare you? Bastard! You lowly piece of trash! You despicable scum!"

"Well……"

Nakime dropped her biwa, her single eye rolled upwards, bloodshot, and her face flushed red, looking extremely pained.

"Ugly and insane, incompetent and cowardly, that twisted soul is utterly repulsive."

Tanjuro Kamado, who was usually not very emotional, looked at Muzan's ugly appearance and showed extreme disgust and revulsion. "Stop torturing your subordinates to vent your anger. The ability to manipulate space is not something that only demons can master."

There seemed to be a white liquid flowing on the surface of Tanjuro Kamado's body, which eventually condensed into a strange armor made of red, black, gold, white and other colors. It looked very angular, hard and majestic.

This is the "Sky Armor" created by Lord Hiruko based on the principles of space science and combined with the characteristics of chakra. It possesses a variety of incredible superpowers, of which spatial teleportation is just one.

"This is the armor bestowed upon me by the Supreme God. It possesses all sorts of incredible abilities, and spatial teleportation is just one of them. Your subordinates have not betrayed you."

Like a fool discarding a giant orange pill, Kamado Tanjuro casually tossed aside his axe, and with his right hand, he grasped a blazing, sun-like golden-red chakra that materialized into a crimson katana that resembled a lightsaber.

This is the "Sun Blade," created by combining Sun Breathing with chakra nature transformation; it possesses immense power.

"What?" Muzan's already distorted face collapsed even further.

Because if Nakime betrayed him, he might still be able to forcibly control Nakime and use her Blood Demon Art to get away from this dangerous human. But since Tanjuro Kamado can teleport, wouldn't he not even have a chance to escape by self-destruction?

He didn't want to believe it, and he dared not believe it.

"Impossible! There are no gods or Buddhas in this world. They are just superstitions of ignorant people. What nonsense are you spouting!" Muzan vehemently denied Kamado Tanjuro's words.

If God really exists, then what is he, a clown? And if the so-called God really exists, then will he be punished...? Muzan dared not think any further. God absolutely does not exist, nor should He exist!

"Since this world has ugly and evil creatures like you, why doesn't it have gods who shine like the sun?" Kamado Tanjuro shook his sword, as if he were shaking off the water droplets from the blade after sharpening it before slaughtering a pig, and a wisp of sparks flew off the blade.

Boom! A sudden burst of flames shot up, thick smoke billowed like ink, and crimson flames mercilessly licked at the wooden house, spreading outwards from there.

The Infinite City, composed of countless Japanese-style pavilions, was instantly ignited by the raging flames, the firelight reddening half the sky.

"Now, the time has come to end you." Tanjuro Kamado, clad in imposing armor, was bathed in flames and thick smoke, his body wreathed in flames, and sword energy emanated from him, tearing apart all the wooden structures around him like a whirlwind.

Its murderous aura was chillingly cold, sending shivers down one's spine.

His powerful fighting spirit remained condensed and did not dissipate; it even materialized behind him, coalescing into a visible, extremely terrifying phantom of a wrathful deity that bore some resemblance to Hiruko.

Hiruko, the scientific ninja, is renowned for his ability to modify life forms and develop ninjutsu. At this moment, his research results seem to be manifesting in Tanjuro.