The Raikage lineage uses the Lightning Release Chakra Mode to constantly temper their bodies, making their physical strength almost the best in the Ninja World without using Ninjutsu.
The Third Raikage, who was later resurrected via Edo Tensei, was able to withstand Naruto's Wind Release: Rasenshuriken with his bare body without using Ninjutsu. His physique was almost invincible. Although an Edo Tensei body can regenerate, he genuinely blocked the Wind Release: Rasenshuriken with his physical body without using Ninjutsu.
Uchiha Nagi walked and pondered. According to a few residual memories from his past life, Breathing Technique wasn't without weaknesses; it seemed to require coordination with breathing during use.
Later, when fighting Upper Rank Two, the opponent's Blood Demon Art could add substances to the air, perfectly countering Breathing Technique.
However, it's not a big problem. Just like Sage Mode, everything has weaknesses; every Jutsu has flaws.
But any weakness can be overcome through training.
The First Hokage directly used Perfect Sage Mode, able to fight while absorbing natural energy. Madara was even more impressive. When he was first resurrected, without a Sharingan or Rinnegan, he single-handedly overwhelmed everyone, then was sealed in a pyramid by Shukaku and immediately activated Susanoo to break the seal.
Activating Susanoo without a Mangekyo? Is that something a human can do?
Uchiha Nagi pondered if Breathing Technique could manifest like Sage Mode.
It's important to know that Sage Mode is the strongest combat mode, created by balancing natural energy, physical energy, and spiritual energy.
Breathing Technique seems somewhat like a combination of natural energy and physical energy, and it's not even the complete version of Breathing Technique.
Therefore, the Hashira of this world have bodies that have surpassed their limits, able to fight immortal demons with their flesh and blood, and use various Breathing Techniques and sword skills to contend with Blood Demon Art.
"Hoo~ It seems I can give it a try." Uchiha Nagi made up his mind. Once his body fully recovers, he will start experimenting.
He will try to create his own Sage Mode by combining physical energy, spiritual energy, and Breathing Technique.
Reaching the peak of Breathing Technique activates a Mark, while Sage Mode has facial markings. Isn't that quite a coincidence?
Because he has no lineage, he can't go to the three great Sage regions to learn how to cultivate natural energy. Besides, he doesn't want to learn it; haven't you seen how high the death rate is?
It would be strange if the death rate wasn't high for human bodies forcibly learning the Sage Arts of summoning animals. Only an idiot would gamble on such a slim chance of success.
And the Breathing Technique of the Demon Slayer World was created by humans, making it the most suitable Sage Art for humans themselves.
Thinking of the strongest Sun Breathing, Uchiha Nagi looked at Tanjiro beside him with burning eyes, making Tanjiro completely bewildered.
"Southeast-South Southeast-South " An annoying crow kept circling over Tanjiro's head, then landed on Tanjiro's shoulder and wouldn't stop squawking.
"I know, I know, stop shouting, ugh, you're practically deafening me." Tanjiro rubbed his ears, then turned to Uchiha Nagi and said, "This is a Kasugai Crow, a companion of the Demon Slayer Corps. Everyone is paired with one as a communication partner."
"Understood," Uchiha Nagi nodded, because there are no cell phones in this world... Suddenly, a loud shout came—
"Please!"
"Please, please marry me, I'm going to die soon~" A person with yellow hair and a yellow haori was kneeling before a girl, begging her to marry him.
"Please, I'm going to die soon, please marry me before I die~" The yellow-haired boy was crying uncontrollably, tears and snot streaming down his face, as if he were about to go to war the next moment.
[Here he comes, Thunder Breathing, Zenitsu Agatsuma...]
Uchiha Nagi quietly watched the boy. He was the same age as Tanjiro, a Demon Slayer Corps member who used Thunder Breathing. He was currently at the lowest rank, but possessed the potential of a Hashira.
The Demon Slayer Corps is divided into ten ranks: Kinoe, Kinoto, Hinoe, Hinoto, Tsuchinoe, Tsuchinoto, Kanoe, Kanoto, Mizunoe, Mizunoto.
Those who just join the Demon Slayer Corps are all at the lowest rank. Above Kinoe are the Hashira, who are currently humanity's highest combat power.
Uchiha Nagi didn't interrupt, watching the two innocent youths have their first comical encounter. In the future, they would become companions through life and death.
After helping the unfamiliar girl get rid of Zenitsu Agatsuma's persistent clinging, Zenitsu Agatsuma stubbornly stuck to Tanjiro, looking utterly terrified of death. It was impossible to imagine that once he fell asleep, this person would transform into a powerful user of Thunder Breathing.
"Eh!! I'm not going, I'm not going~ I won't go no matter what." Zenitsu Agatsuma cried, clinging tightly to Tanjiro's leg.
"Zenitsu, you're not going? Why are you so shameless? Think about why you became a Demon Slayer Corps member," Tanjiro said angrily.
"I never wanted to be a Demon Slayer Corps member. I was tricked by a woman and fell into debt. The old man who paid off my debt was a trainer, and then it was hellish training, training, and more training every day."
Zenitsu Agatsuma clasped his hands over his head, "I'm definitely going to be eaten by a demon. My brains will be sucked out of my ears before I even die. I don't want to, save me~~~"
He cried and shouted—
Beside him was his exclusive Kasugai Crow, a unique sparrow, chirping and complaining on Tanjiro's shoulder.
Watching Tanjiro nod and agree, Uchiha Nagi roughly guessed the content: it was nothing more than its master being afraid of death, not daring to go when a demon appeared... Uchiha Nagi envied Tanjiro's ability to communicate with animals. His crow could talk, but this sparrow couldn't.
Clearly, Zenitsu, like Tanjiro, possessed some peculiar abilities to communicate with animals. Oh, and this guy also had super hearing.
"In the southeast direction, in a house, a target has appeared. Demon Slayer Corps members have already gone there. Let's hurry and depart."
Then Tanjiro, pulling the still crying Zenitsu, set off with Uchiha Nagi.
After some time to calm down, Zenitsu still followed behind them with a look of utter despair.
After walking for a few hours, the three arrived outside a house. Tanjiro saw two children in the woods and ran over to ask them. Just then, a corpse flew out of the house.
Uchiha Nagi ran over. The man who flew out was already on his last breath and died after only a few words. Such injuries could not be saved even with Medical Ninjutsu.
"If only we had come sooner, damn it, we couldn't save him." Tanjiro brought the two children and explained to Uchiha Nagi that they were the ones involved, and their older brother had already been taken into the house by a demon.
Drawing his nichirin blade, Tanjiro was about to rush in but was stopped by Uchiha Nagi.
"A wooden house? We could try burning it. They're afraid of sunlight." Uchiha Nagi began to form hand seals. His White Zetsu arm had perfectly healed after two days. Now he could move, though the bone connections weren't yet that solid.
"Fire Release: Great Fireball Jutsu." Uchiha Nagi used his Good at Fire Release Ninjutsu, intending to burn down the house and force the demon inside out. Having stayed in the Ninja World for so long, he subconsciously felt there were traps whenever he entered a house with enemies. [PS: When Madara was first resurrected, his Edo Tensei Rinnegan shattered, and he fought the Tailed Beasts with his eyes closed. He was sealed in a pyramid by Shukaku and broke out with Susanoo. At this time, he didn't even have his Mangekyo Sharingan.]