Although Mutsuki already has a Basic Breathing Technique that provides a modest enhancement in strength, he will not teach the Basic Breathing Technique to anyone other than his disciples, unless he trusts them.
The Basic Breathing Technique, though it offers only limited improvement, is considered one of the core techniques within Breathing Techniques, with significant potential for further development. Mutsuki's efforts to create other breathing techniques also begin with the Basic Breathing Technique.
To illustrate with numbers, mastering the Basic Breathing Technique up to Constant can only bring a sixty-point combat power boost to the ANBU and Root members.
However, if a genius from Sarutobi Hiruzen's or Shimura Danzo's faction were to unlock the potential of the Basic Breathing Technique and develop something akin to Mutsuki's Stone Breathing or Thunder Breathing, the upper limits would increase significantly, potentially resulting in a Breathing Technique that could boost combat power by as much as five hundred points.
Mutsuki doesn't underestimate the ninja of the Naruto World just because he is a transmigrator with a system.
Someone as powerful as Senju Tobirama, who developed numerous formidable ninjutsu and forbidden techniques, would likely create a new forbidden technique if given the Basic Breathing Technique, in Mutsuki's opinion.
Teaching the Basic Breathing Technique to the ANBU and Root could result in a genius eventually developing an advanced Breathing Technique, which might ultimately end up aiding his enemies—something Mutsuki does not want to see.
Currently, Mutsuki has no apparent conflicts with Sarutobi Hiruzen, Shimura Danzo, or the Konoha Elders, and both Root and ANBU are not his enemies. However, he can't say for sure what the future holds.
The Breathing Technique Mutsuki aims to develop will enhance combat power by one hundred points at the Proficient level, but that's the limit; further improvement would be impossible without a path forward.
By developing a new Breathing Technique, Mutsuki can earn better rewards and also avoid aiding his enemies. Given his considerable experience in developing Breathing Techniques, combined with his Enlightenment state, this task isn't difficult for him.
...
"Minato-sensei."
In the training ground, Kakashi, Obito, and others greeted Minato, who was smiling.
With the completion of Guy's life mission, Mutsuki's special training goal was achieved, so a few days later, Mutsuki announced that the special training had successfully concluded. Except for Shisui, who hadn't graduated yet, everyone returned to their respective teams.
"I'm truly sorry; as a sensei, I haven't been as competent as Mutsuki," Minato said apologetically.
Although he was the guiding sensei, it was primarily Mutsuki who helped Obito and the others grow.
"It's different, though. Besides, Minato-sensei, you're taking on missions to protect the village," Obito reassured him, saying there was no need for Minato to worry about such things.
"Obito's right; there's no need to apologize, Minato-sensei," Rin agreed, nodding.
Originally, she should have been training with Tsunade, but since it had been a while since she trained with Minato as her guiding sensei, Rin asked Tsunade for a day off.
"Not bringing us along on missions is also for our safety," Kakashi said, showing understanding of Minato's decision.
In Kakashi's eyes, Minato was also a very reliable ninja.
Hearing Obito and the others' words, Minato's face lit up with a genuine smile; he was beginning to understand the joys of being a sensei.
"Minato-sensei, are we training or taking on a mission today?" Obito asked as he noticed Minato's mood had improved.
"Let's start with some training. I'll first test your current strength," Minato replied after some thought.
Not much time had actually passed, and typically, a ninja's growth rate wouldn't show much change in that short time. But Kakashi and Obito clearly weren't in the normal category, so he decided to begin with a combat training session.
"Do we have to fight you, Minato-sensei?" Obito scratched his head and asked again.
He wasn't too eager to fight Minato; fighting him was always frustrating. It was easy to get beaten up without even landing a hit, which made him feel rather silly.
Minato nodded in agreement.
"Minato-sensei, could you bring in a Konoha Jonin for us to spar with? I think fighting different ninjas would better train our adaptability," Obito suggested.
Since becoming an intern, Obito had already sparred with several Jonin, like the Hidden Cloud Jonin encountered on a mission with Mutsuki, the Mist Jonin he met in the Chunin Exams, and Kazahana Doto in the Land of Snow, who could also be considered a Jonin. Obito felt he could hold his own in front of a Jonin.
Minato thought it over and agreed that Obito had a point, and since he knew quite a few Jonin, it wouldn't be hard to find one.
"Wait here for a bit; I'll be right back." Leaving those words, Minato disappeared in front of the three.
First, he went to find Dekai, a fellow member of Jiraiya's team.
Although he knew many Jonin, Minato would naturally prioritize those he was closer to.
Minato was lucky; Dekai was at home and hadn't gone out on a mission or to have fun.
"Help you test your students' strength? Leave it to me," Dekai agreed immediately after hearing Minato's request.
"My students are fairly capable, so no need to hold back too much," Minato reminded him, thinking of something.
He remembered that Dekai had been on a mission during the Chunin Exams, so he hadn't seen them.
"Well, they are your students after all," Dekai chuckled, giving Minato a light punch on the chest without giving it much thought.
In his view, while Minato was undeniably strong, his students had only just graduated this year; even if they were talented, they couldn't be that strong.
Dekai was no genius like Minato, but he was considered quite strong among the Jonin. He didn't believe a few recently graduated ninjas would give him much trouble.
"Thanks, then," Minato smiled in gratitude and used the Flying Thunder God Jutsu to bring Dekai back to the training ground.
"Dekai-san." Obito and Kakashi greeted Dekai when they saw him.
They weren't strangers to Dekai; they had even shared some insect cuisine from Mount Myoboku's sages together on the battlefield in the Land of Grass.
Dekai laughed heartily and patted Obito and Kakashi on the shoulders.
"Obito, you're something else, becoming a Chunin so quickly." Dekai looked at Obito's Chunin vest with some surprise.
By the timeline, Obito had become a Chunin within just a few months of becoming a ninja.
"Not too bad; the Chunin Exams weren't that hard," Obito replied with a grin.
Since even Asuma, whom he defeated, had become a Chunin, Obito indeed didn't find it too challenging.
"Looks like I'll have to put in a bit more effort, then." Dekai noticed that the unfamiliar Rin was also a Chunin, making them a Chunin team.
"Rin-chan, we know Dekai-san from the battlefield," Obito explained when he noticed Rin's slight confusion.
Rin nodded thoughtfully, realizing it must have happened during their time as intern ninjas.
After chatting for a while, it was time for training.
"I'm skilled in Lightning Release NinTaijutsu, which is quite powerful. If any of you feel you can't keep up, step out immediately, or you might get hurt," Dekai said as the battle was about to begin.
"Dekai-san, you don't need to worry. Rin-chan's Medical Ninjutsu is amazing; even if we get injured, she can heal us," Obito said proudly.
"If you think my healing is so great, then don't try to act tough when you're hurt," Rin retorted with a sigh.
"Well… that's because I'm actually not hurt," Obito stammered, his cheeks turning red.
He wanted to show his coolest side to Rin, so sometimes he wouldn't admit he was injured.
"How pure," Dekai remarked, looking at Obito and then at Rin, feeling nostalgic for his own lost youth.
Then he remembered he never had a close female classmate, and quickly brushed off the thought.
"Begin training!" Minato called out as both sides prepared themselves.
"Flame Breathing, Total Concentration!"
"Thunder Breathing, Total Concentration!"
Kakashi and Obito immediately heightened their breathing to full concentration.
Kakashi had never seen Dekai go all out; he had clearly held back when sparring with Guy. But Dekai was Minato's teammate and a student of Jiraiya, so Kakashi believed Dekai's strength couldn't be underestimated.
Since Rin had been busy learning Medical Ninjutsu with Tsunade, Obito hadn't seen her much lately. Wanting to show off in front of her, he went all out.
"Flame Breathing Chakra Mode!"
Obito concentrated his breathing to the limit, causing his chakra to surge wildly, and his aura rapidly intensified.
As a Jonin facing opponents who were barely ten years old, Dekai naturally didn't make the first move to gain the upper hand.
But as Obito entered his Flame Breathing Chakra Mode, Dekai sensed something was off.
Sensing the intense heat not far from him, Dekai showed a look of confusion. Was this really a ninja who had graduated less than a year ago?
"Fire Release: Great Fireball Jutsu!"
Obito quickly formed hand seals, transforming a large amount of chakra into fire chakra, and unleashed it all in one breath.
Whoosh!!
The fiercely burning orange flames rapidly accumulated, ultimately forming a giant fireball that hurtled toward Dekai.
Dekai reflected on his ninja career, thinking that such a powerful Great Fireball should not be something a newly graduated Chunin could produce.
In that moment, he even doubted that it was Uchiha Obito standing across from him and wondered if it was a Konoha Jonin skilled in Fire Release using Transformation Jutsu.
Although he could handle it, Dekai wasn't interested in taking on a ninjutsu that he could easily evade. He gathered chakra in the soles of his feet, preparing to dodge.
"Flash!"
At that moment, Kakashi drew his White Fang Tanto, converting all the chakra gathered in his legs into lightning chakra, and charged toward Dekai.
Now, they could coordinate at this level without any verbal communication, just a glance was enough.
If Obito's powerful presence surprised Dekai, Kakashi's speed truly left him in shock.
Looking at the bloodstains on his arm, Dekai felt an immense surprise in his heart.
Even though it was a combined attack, he was still considered strong among Konoha Jonin; it was unbelievable that he had been injured by a child under ten.
When he had dodged the Great Fireball, Kakashi had suddenly charged out. He hadn't anticipated Kakashi's speed to be that fast, and he hadn't been able to evade in time.
Dekai dismissed his previous underestimation; although he didn't know what was going on, Minato's three disciples were all quite formidable. If he didn't take this seriously, he might actually lose.
He certainly didn't want to lose; if Sohei found out, he would never hear the end of it.
With a flicker of his gaze, Dekai scanned all three of them and quickly devised a battle plan, then unleashed his chakra as Obito charged in.
With his body enhanced by lightning chakra, Dekai's somewhat plump physique displayed surprising speed.
Seeing this, Obito activated his Sharingan to enhance his dynamic vision, while Kakashi silently gathered chakra, preparing to assist Obito in relieving the pressure of the attack.
But just as Dekai was about to approach Obito, Obito had already gathered a large amount of flames in his hand, and Kakashi was also releasing lightning toward Obito's front.
In that instant, Dekai suddenly slammed to a stop and struck the ground with a fist charged with lightning.
Boom!
The explosion sounded as the terrifying force blasted the ground, sending mud and debris flying everywhere. Immediately after, Dekai charged toward Rin, swinging a heavy fist at her.
At the beginning, Obito had mentioned that Rin was a medical ninja, and since she hadn't made a move during the previous attack, Dekai assumed that her role in the team was to provide healing and that her combat ability was poor. Therefore, he didn't enhance his body with lightning chakra.
Obito's Sharingan clearly saw Dekai's actions, but when he saw Dekai throw a punch at Rin without using any ninjutsu, he didn't intervene and internally mourned for Dekai for a second.
"Enhanced Strength Fist!"
Rin concentrated a large amount of chakra in her fist and then struck out, colliding with Dekai's punch.
Bang!
Dekai's expression twisted slightly as he felt an immense power erupting from Rin's slender frame, like that of a monster.
Thanks to his solid physical conditioning, Dekai managed to withstand the blow for a moment before being sent flying backward by the overwhelming force.
As he flew away, Dekai shot a resentful glance at Minato, thinking, "Is this what you call 'not bad'?"
"What were you thinking? You didn't even use chakra and just exchanged blows with Rin-chan," Obito said, recalling how Rin had once punched through a thick tree, sending a chill down his spine.
How painful would that punch be?
Although it was training, it was still a battle, and Kakashi and Obito immediately seized the opportunity to attack.
Obito consumed a large amount of chakra, unleashing a wave of flames that surrounded Dekai from multiple angles.
Kakashi entered the Transparent World state, transforming a significant amount of chakra into lightning chakra to enhance his body, pouring all his strength into the White Fang Tanto as he locked onto Dekai.
"Cough, cough, training is over." Minato cleared his throat and ended the training early.
"I know, it was because of a lack of information," Minato said to console him before he could even speak.
Dekai: ...
That was indeed the case. If he had known that Obito and Kakashi had such strength, he would have given it his all from the start. If he had known that Rin possessed such terrifying power, he definitely wouldn't have chosen to go barehanded against her.
Although Minato was speaking the truth, Dekai felt a faint sadness in his heart. He had actually lost to three kids under ten years old, and they were also his friend's disciples.
Dekai walked away, leaving Minato and the others with a lonely silhouette.
"If you need me next time, just let me know. I'll bring Sohei along," Dekai suddenly stopped and said.
The more he thought about it, the angrier he became. In a normal fight, he would almost never lose, but because of his underestimation and lack of information, he had lost. So, Dekai decided to let his good friend experience this feeling.
Minato nodded with a smile.
Sohei was also a member of Jiraiya's team, and his strength was comparable to Dekai's.
Since Dekai's battle ended too quickly and the training objectives were not met, Minato ultimately decided to fight himself.
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