The Raikage lineage uses Lightning Release Chakra Mode to constantly temper their bodies, making their physical bodies almost the best in the ninja world when they don't use ninjutsu.
The Third Raikage, resurrected later using Edo Tensei, was able to withstand Naruto's Wind Release: Rasenshuriken without using ninjutsu, demonstrating his almost invincible physical body. Although the Edo Tensei body can be restored, he genuinely blocked the Wind Release: Rasenshuriken with his bare body without using ninjutsu.
As Uchiha Nagi walked, she pondered. Based on the few remaining memories from her previous life, she realized that breathing techniques were not without weaknesses; it seemed that they had to be coordinated with breathing techniques when used.
Later, when fighting Upper Moon Two, the opponent's Blood Demon Art could add things to the air, perfectly countering the Breathing Technique.
However, it's not a big problem. Just like magic, it has weaknesses. Every technique has its flaws.
However, any weakness can be overcome through training.
The First Hokage directly achieved perfect Sage Mode, allowing him to absorb natural energy while fighting. Madara was even more impressive. Upon his resurrection, without the Sharingan or Rinnegan, he utterly dominated the entire battlefield before being sealed in a pyramid by Shukaku, where he activated Susanoo to break the seal.
Opening Susanoo without the Kaleidoscope? Is that even possible for a human?
Uchiha Nagi was pondering whether breathing techniques could be presented like Sage Mode.
It's important to know that Sage Mode is the strongest combat mode created by balancing natural energy, personal energy, and spiritual energy.
The breathing technique seems to be a combination of natural energy and one's own energy, but it is not the complete version of the breathing technique.
Therefore, the Pillars of this world have all surpassed the limits of physical strength, enabling them to fight against immortal demons with their flesh and blood, and to use various breathing techniques and sword skills to contend with Blood Demon Art.
"Phew~ Looks like I can give it a try." Uchiha Nagi made up her mind and waited for her body to recover to 100% before she began to try.
He attempted to create his own immortal mode by combining physical energy, mental energy, and breathing techniques.
Reaching the peak of breathing techniques unlocks markings, while immortal techniques have facial masks. Isn't that a coincidence?
Because he lacks the lineage, he cannot go to the three holy lands and obtain the cultivation methods of natural energy. Besides, he doesn't want to learn them either, given how high the mortality rate is.
Forcing a human body to learn the magical arts of a summoned beast is bound to result in a high mortality rate; only an idiot would gamble on such a slim chance of winning.
The breathing techniques of the Demon Slayer world were created by humans and are the most suitable sage techniques for humans themselves.
Thinking of the strongest Sun Breathing technique, Uchiha Nagi looked at Tanjiro beside her with a burning passion, leaving him completely bewildered.
"Southeast South~ Southeast South~" An annoying crow kept circling above Tanjiro's head, then landed on his shoulder and kept cawing.
"Okay, okay, stop yelling. Ugh, you're killing my ears." Tanjiro rubbed his ears and turned to Nagi Uchiha, saying, "These are Kasugai crows, companions of the Demon Slayer Corps. Each person is paired with one as a communication partner."
"Yes, I understand." Uchiha Nagi nodded, because there were no cell phones in this world…
Suddenly, a loud shout rang out—
Please~
"Please, marry me, I'm dying~" A man with yellow hair and a yellow feather robe was kneeling in front of a girl, begging her to marry him.
"Please, I'm dying, please marry me before I die~" The blond boy cried uncontrollably, tears and snot streaming down his face, as if he were about to go to war.
[Here it comes, Thunder Breathing, Zenitsu Agatsuma...]
Uchiha Nagi quietly looked at the boy. He was the same age as Tanjiro, a member of the Demon Slayer Corps using the Thunder Breathing technique, currently at the lowest rank, but possessing the potential of a Pillar.
The demon-slaying teams are divided into ten ranks: A, B, C, D, E, F, G, H, I, and G.
Those who have just joined the Demon Slayer Corps are all at the highest level, above the Rank 5, which is the Pillar, representing the highest fighting force humans have ever possessed.
Uchiha Nagi didn't interrupt, watching the two innocent boys having their first silly encounter, knowing they would become comrades-in-arms in the future.
After helping the stranger girl escape Zenitsu's clutches, Zenitsu clung to Tanjiro, acting like a coward, completely unimaginable that this man would become a powerful user of Thunder Breathing as soon as he fell asleep.
"Ew!! I'm not going, I'm not going~ I'm not going no matter what." Zenitsu Agatsuma cried and clung tightly to Tanjiro's leg.
"Zenitsu, aren't you going? Why are you so shameless? Think about why you joined the Demon Slayer Corps in the first place!" Tanjiro said angrily.
"I never wanted to become a demon slayer. I was tricked by a woman and ended up in debt. The old man who paid off my debt was a trainer, and every day was hellish training, training, and more training."
Zenitsu Agatsuma covered his head with his hands, crying, "I'm going to be eaten by demons! My brains will be sucked out of my ears before I even die! I don't want to! Help me!"
Crying and shouting—
Beside him was his personal Kasugai-rabbit, a sparrow unlike any other, chirping and complaining on Tanjiro's shoulder.
Seeing Tanjiro nodding and agreeing, Nagi Uchiha roughly guessed what was going on: its master was afraid of dying and didn't dare to go if a demon appeared...
Nagi Uchiha was envious of Tanjiro's ability to communicate with animals; his crow could talk, but this sparrow couldn't.
Zenitsu, like Tanjiro, clearly possesses some unique ability to communicate with animals. Oh, and this guy also has super hearing.
"The target has been spotted in a house in the southeast direction. Members of the Demon Slayer Team have already gone there. Let's set off quickly."
Then Tanjiro, holding Zenitsu who was crying, set off with Nagi Uchiha.
After a period of calming down, Zenitsu still followed behind them with a look of utter despair.
After walking for several hours, the three arrived outside a house. Tanjiro saw two children in the woods and ran over to ask them what was wrong. Just then, a corpse flew out of the house.
Uchiha Nagi ran over, and the man who had been thrown out was already on the verge of death. He died before he could say two words. Even medical ninjutsu couldn't save him from this kind of injury.
"If only we had come sooner, damn it, we couldn't save him." Tanjiro brought two children and explained to Uchiha Nagi that they were the ones involved, and that the older brother had been taken into the house by a demon.
Tanjiro drew his Nichirin Blade and was about to rush inside when Nagi Uchiha stopped him.
"A wooden house? We can try burning it down. They're afraid of sunlight." Uchiha Nagi began forming hand seals. After two days, White Zetsu's arm had healed perfectly and he could move it now, although the bone joints weren't quite strong yet.
"Fire Release: Great Fireball Technique!" Uchiha Nagi used her signature Fire Release ninjutsu, intending to burn the house down to force out the demons inside. Having spent so much time in the ninja world, she subconsciously felt a trap when entering a house with enemies.
[PS: When Madara was first resurrected, his Edo Tensei Rinnegan was shattered. He fought the Tailed Beasts with his eyes closed, was sealed in a pyramid by Shukaku, and was forced out using Susanoo. At that time, he didn't even have his Mangekyou Sharingan.]