"So, when a Shadow Clone is dispelled, the memories of its experiences are transmitted back to the original body. Therefore, besides the memories of 'death,' there are also memories of training."
Uchiha Nagi continued, "Thus, if you use ten Shadow Clones to train, your speed will be equivalent to ten times the normal rate. Understand?"
Muichiro's eyes widened in disbelief. "I see! No wonder Uchiha-san is so strong. Do you train at ten times the speed every day? You're truly a genius."
"Ahem..." Uchiha Nagi felt a bit embarrassed by his praise. "It works for other types of training, but for Breathing Styles... I've tried, and it doesn't seem to work."
Uchiha Nagi sighed helplessly and explained the nature of Shadow Clones to Muichiro: they were essentially formed from chakra and lacked internal organs. Therefore, it was very difficult for Shadow Clones to perform Breathing Styles, which required simulated breathing to control the entire body's muscles and blood flow...
However, they were excellent for practicing other things, like ninjutsu.
After Uchiha Nagi's explanation, Muichiro departed with a grateful expression. It was certain that he would become even stronger by accelerating his ninjutsu training.
Over the next few days, Uchiha Nagi began to consolidate the Breathing Styles he had learned during this period. Among them, he was most proficient in Water Breathing.
Then there was Flame Breathing, which he had become skilled in thanks to the Flame Hashira's guidance over the preceding days, coupled with the copying he did during the battle against Akaza that night. He could be considered reasonably proficient.
What amazed Uchiha Nagi the most was the First Form of Thunder Breathing, an insight he had gained from Zenitsu.
Later on, Zenitsu was able to develop techniques like Thunderclap and Flash Sixfold, Eightfold, and Godspeed, all based on the single Thunderclap and Flash form. This showed Uchiha Nagi a different path.
Because the First Form of Thunder Breathing was solely about speed, Zenitsu had directly developed a compound First Form, allowing him to flash multiple times in one go. Uchiha Nagi, possessing the Mangekyo Sharingan, had no problem with dynamic vision; he too could become a "Yellow Flash"—
Uchiha Nagi activated the Thunder Breathing method, took a deep breath, and the next second, activated his three-tomoe Sharingan's dynamic vision.
"Thunder Breathing, Thunderclap and Flash—Eightfold!"
In an instant, a golden streak of lightning flashed past the eight training dummies in the courtyard. A cut mark appeared on the necks of all of them. The entire process took less than a second.
"It's still not enough. These eight dummies are all placed together. What if the enemies are widely dispersed?" Uchiha Nagi muttered to himself.
Ninjas wouldn't all gather in one spot during a battle, as that would make them easy to wipe out in one go. If they were scattered, a single form naturally couldn't behead all of them in one move.
"It's still not as fast as the Flying Thunder God technique..."
The Flying Thunder God technique also had its drawbacks: it definitely required a marker. His own Mind Teleportation didn't, but the eye power consumed for interdimensional travel was too great. If he returned once, he wouldn't be able to use Mind Teleportation for at least a year. The chakra-consuming space-time ninjutsu, Flying Thunder God, was certainly cheaper and more practical. So, if he were to go back, he would definitely have to find a way to obtain it.
"Sugoi~ Nagi-aniki! Was that... an Eightfold Flash??" A certain yellow-haired kid peeked his head out, watching Uchiha Nagi.
"Mm. I saw you use a Sixfold Flash on the train that day, so I was inspired," Uchiha Nagi said.
"Is that so? I really am useless... Waaah, ~~" Zenitsu squatted on the ground, clutching his head and sobbing.
Uchiha Nagi: "....."
Seeing this incredibly talented idiot about to spiral into self-pity, Uchiha Nagi had no choice but to walk over and console him.Seriously? If his talent wasn't strong, would the retired Thunder Hashira personally teach him?
"Zenitsu, if you want to learn, I'll teach you. You have a talent hidden within you that even you aren't aware of. You just haven't discovered it yet," Uchiha Nagi said truthfully.
To be able to innovate a new form upon the nearly complete Thunder Breathing, which had been passed down for hundreds of years, his talent was undoubtedly exceptional.
"Really? Thank you so much, Nagi-aniki! Oh, right, I almost forgot. Miss Shinobu asked me to bring someone over," Zenitsu said, then waved to someone behind him.
A young man with a ferocious scar on his face and sharp eyes, looking every bit like a delinquent, walked over with his head lowered.
"Hello, I am a newly promoted Demon Slayer Corps member, Shinazugawa Genya." Unexpectedly, Shinazugawa Genya was very polite towards Uchiha Nagi.
"Genya?! I know you! You were one of the few survivors from the Final Selection that day," Zenitsu said curiously.
Uchiha Nagi nodded. "Hello, I am Uchiha Nagi. Is there something specific you came to find me for?"
Shinazugawa Genya kept his head down, seeming to find it difficult to speak.
"I... I want to learn ninjutsu and chakra from you..."
"Haven't I already given the basics of chakra study to the Demon Slayer Corps?"
Uchiha Nagi himself was busy training various Breathing Styles every day, and after training, he still had to conduct research on demon genetics. He really didn't want to take on a student. They didn't know each other, so naturally, he wouldn't spend time teaching someone else for no benefit whatsoever...
"Is that so~ My apologies for bothering you..." Shinazugawa Genya's face turned red. He bowed, then ran off in a fluster.
"Eh? Why did that guy leave after just a few words?" Zenitsu scratched his head, puzzled.
"Probably his pride getting in the way..." Uchiha Nagi understood. Teenagers valued their pride the most. They couldn't let go of their pride yet still wanted others to be their teacher. It just didn't work out. Uchiha Nagi had always believed in equivalent exchange. If it wasn't an equivalent exchange, then it would depend on his mood.
Since he left, Uchiha Nagi paid him no further mind. If one couldn't be shameless like Naruto, nor willing to risk their life like Sasuke, they naturally wouldn't learn anything.
In the courtyard, he trained with Zenitsu for over an hour. Zenitsu was indeed a genius with extremely high hidden talent. For Thunder Breathing, he only knew the First Form, Thunderclap and Flash. But through years of using it, he had comprehended something different within that First Form, developing a two-hit combo. However, limited by his physique and dynamic vision, he could currently only manage a twofold flash.
"Because your body is still developing, don't rush to develop subsequent moves. Overexerting a developing body is not a good thing," Uchiha Nagi advised.
Zenitsu was still a teenager, the same age as Tanjiro. His body still had a long period of development ahead. Appropriate training would aid development, but excessive training could instead leave hidden injuries.
In Uchiha Nagi's view, the destructive power and speed of Thunderclap and Flash were somewhat similar to Chidori. The fact that he could easily develop it to a sixfold flash after seeing Zenitsu's twofold flash was thanks to his Mangekyo's powerful dynamic vision and the White Zetsu cells. The White Zetsu cells were continuously strengthening his constitution. Now, his chakra was increasing day by day, causing Uchiha Nagi, who was past his growth period, to undergo a second phase of development.
After Zenitsu left, Uchiha Nagi silently turned his head towards the rooftop and said, "Everyone's gone. Aren't you coming out yet?"