Afterward, Natsunishi began to guide the trio in their Breathing Styles one by one. His goal was not to correct the conflicts between their personal habits and the standard Breathing Styles. Since a derived Breathing Style was the "optimal solution" tailored to an individual, why force them to suppress their unique traits just to adapt to a standard model?
Of course, he would provide a custom version for each of the three youngsters!
Kyojuro was a person unlike Shinjuro or even Dojima. His will was purer, and his nature more "upright." The latter two, when using Flame Breathing, did not shy away from using deceptive techniques or varied sword skills; they would even resort to external tools in a crisis. If it were for the sake of slaying a demon, they would likely use Uzui's bombs or poisons if given the chance.
But Kyojuro would almost certainly refuse. He wouldn't stop his comrades from using such means, but he himself would always choose to push his own limits even further, using his burning will to win a fair and square victory. He was as passionate and open-hearted as a traditional Flame Breathing swordsman, yet Kyojuro possessed a touch more "single-mindedness" and "directness."
This was both a limitation and his defining trait. Natsunishi did not doubt for a moment that while other Flame Breathing swordsmen might lose their spirit in a desperate situation, Kyojuro never would. He was the kind of child who, even in the face of death, would walk straight forward and never look back.
If the traditional Flame Breathing constrained that stubbornness, Natsunishi didn't mind forging a new path for him.
"Come, use your Flame Breathing, and then adjust to the rhythm I describe."
Natsunishi placed a stone on Shinjuro's wooden sword. His other hand was pressed against Kyojuro's abdomen.
"Standard Flame Breathing is about letting the flames burn to illuminate and dispel the darkness, much like a torch. It is continuous, constantly adjusting and changing according to the outside world."
Natsunishi operated the same Breathing Style, slowly shifting the melody while carefully choosing his words. "Can you feel it?"
Kyojuro struggled to keep the wooden sword steady to prevent the stone from falling, but he still shouted loudly, "Forgive me! Big Brother Natsunishi! Aside from the temperature of your hand and the wobbling of the stone, I feel nothing at all!"
Just as the other's breathing rhythm changed, Natsunishi's palm suddenly exerted force. The "Owl Boy's" breath was forced to surge outward violently. The rhythm of the Breathing Style changed. Simultaneously, the stone on the sword was suddenly flicked into the air.
Natsunishi picked up another stone and replaced it. "Try it the way I say. Let the rhythm of your breathing fluctuate violently along with your fighting spirit. There's no need for too many variations; two are enough. With the will to protect, keep the stone on your wooden sword as steady as can be. But when you swing the sword, it must be like an explosion. Not a continuous burn like a flame, but fire. A blade that decapitates the opponent in the shortest possible time—a flow of fire that burns everything out. Don't flick the stone away; cut it in half."
This involved a specific, short, and intense inhalation following an ultra-deep breath. It pushed the cardiopulmonary function to the limit. It compressed the torch, which was supposed to burn over a long period, into a single moment of explosion.
It shared similarities with Thunder Breathing, as both were techniques for bursting into a powerful state within a short timeframe. However, it largely remained within the Flame Breathing lineage, emphasizing the upper limbs, waist, and back, whereas Thunder Breathing focused more on the lower limbs and arms.
As he adjusted the other's breathing rhythm, Natsunishi glanced at the system panel. His experience from exploring so many Breathing Styles was enough to allow him to perform "addition and subtraction" while standing on the shoulders of giants. As for the effect—he was counting on his Lvl 2 [Instruction] to deliver. Great Success, Great Success! Come on, give it to me!
To the side, Iguro and Shinobu exchanged a glance. Iguro lowered his voice, "Is Senior's method... truly feasible?" Though it looked impressive, he had some doubts about whether the other actually possessed the ability to modify a Breathing Style.
Shinobu, however, harbored no doubt at all. She watched every detail of Natsunishi guiding Kyojuro intently, just as she watched Natsunishi himself.
"Kuguruma-kun has already mastered six Breathing Styles, and his Total Concentration in almost every one far exceeds that of an ordinary swordsman. Not long ago, he suppressed and slew Lower Moon Five in a head-on confrontation. Even if he isn't some unprecedented combat genius or the so-called 'strongest swordsman'—" She paused slightly, her smile carrying a certain undeniable certainty. "He is surely, to this day, the one who understands Breathing Styles most deeply... A Breathing Style Expert."
Having said this, she turned to Iguro with a beaming smile. "So, Iguro-san, please do not question Kuguruma-kun's professionalism, okay?"
Iguro and the small snake wrapped around him both shrank their necks. Women... were a bit terrifying. He looked back at Natsunishi, attempting to set aside his doubts. A Breathing Style Expert? If someone truly mastered so many styles and possessed such exceptional strength, perhaps through interdisciplinary understanding, they really would know how to calibrate the rhythm of breathing better than a swordsman who studied only one.
"Senior, is it my turn for Breathing Style guidance next?" Once Kyojuro seemed to have entered the right state and Natsunishi freed his hands, Iguro finally spoke up.
Natsunishi looked at the boy with the somewhat gloomy temperament. I really want him to take a Kusanagi sword and learn Ninjutsu...
"Ahem, Little Orochimaru, you are currently practicing Water Breathing, right?"
The bandaged boy argued in a small voice, "It's Iguro."
Natsunishi acted as if he hadn't heard and continued, "Your situation is somewhat similar to Shinobu's; you both lack strength in your hands and upper limbs. Although Water Breathing can accommodate the vast majority of physiques, if you want to go further after reaching a certain level... you likely have no choice but to take the path of developing a unique derived Breathing Style."
Water Breathing emphasized a continuous sense of flow, as well as the inclusiveness and adaptability to overcome hardness with softness. To put it bluntly, it didn't require an exaggerated physique, but it also couldn't have any obvious shortfalls. Iguro's upper body strength was qualified for an ordinary swordsman, but if he wanted to become a Hashira using Water Breathing, the hardship and effort required would far exceed those of others.
As for his hand muscles developing further? Based on Natsunishi's medical expertise, even if Iguro's body developed and trained for a while, his growth rate would likely never catch up to swordsmen with extraordinary natural talent. Men like Tengen, Kyojuro, or even Sabito and Giyu—once they entered the peak of physical development, their arm strength, wrist strength, and grip would all grow rapidly. Unless he had a special means of augmentation, it would be difficult for Iguro to keep up with them.
"Then does Senior have any suggestions?"
Natsunishi: "Ambush them."
If being a high-attack speed, high-health, or high-damage warrior didn't fit, the first thing he thought of was a high-crit, backstabbing technical assassin. He had noticed during this time that unlike Shinobu, who specialized in poison, this boy happened to enjoy using unconventional moves in combat. Perhaps, rather than Water Breathing, Wind Breathing—which focused on speed and cutting—would suit him better.
"Do you have any preferences or ideas of your own?"
Iguro said uncertainly, "I suppose... I like finding the opponent's weaknesses? I'm not good at head-on clashes with enemies." After speaking, he looked at Kaburamaru on his shoulder. That was the companion who had accompanied him out of that hell. If possible, he wanted to be like it—hidden in the darkness, waiting for the right moment, needing only to deliver a fatal blow to the enemy at the critical second.
"Then try focusing on strengthening your lower body and footwork. If your strength isn't enough, you can try shifting your body's center of gravity onto the blade to increase the penetration of your slashes—" Natsunishi noticed Iguro's gaze. "A snake? What, do you and it have some kind of hot-blooded combo technique?"
Iguro: "..."
After a moment of silence, he informed Natsunishi of his thoughts. Combat methods related to snakes...
"Start by getting a custom-made weapon, and then smear it with deadly poison." That fit the stereotype of a snake perfectly.
Iguro couldn't help but retort, "Senior, what we are practicing right now is a Breathing Style."
Only then did Natsunishi chuckle and begin to adjust the rhythm of his breathing.