No one expected Kuguruma Natsunishi's mastery of Water Breathing to advance by leaps and bounds as if he had experienced a sudden epiphany.
In just a single night, he leapt from an apprentice who hadn't even touched the threshold to a level nearly high enough to graduate.
Kuguruma Natsunishi's current Water Breathing was already on par with Giyu Tomioka.
This was the conclusion Sakonji Urokodaki reached after personally testing him. It forced the old man to admit that Kazami Sarayoshi had indeed chosen well.
In a mere ten days, building upon his mastery of Wind Breathing, Kuguruma Natsunishi had fully mastered a completely different breathing style. This child was a genius through and through.
While Sabito and Giyu were stunned, they were more sincerely happy for Kuguruma Natsunishi. Though they had been beaten black and blue during their training these past few days, they felt their strength growing rapidly. Living together day and night had forged a genuine bond of friendship between them and Kuguruma Natsunishi.
However, after the initial joy, the two young boys soon realized that their time together was coming to an end. Kuguruma Natsunishi had come to study Water Breathing. Having achieved his goal, his departure was only natural.
After Urokodaki had a Kasugai Crow send word back to Kazami, Kuguruma Natsunishi was in no hurry to say his goodbyes. Instead, he made two requests of Urokodaki.
First, before his Demon Slayer Corps mission arrived, he hoped to stay for a while longer. Not for breathing techniques, but to practice life skills.
Kuguruma Natsunishi had long noticed that besides being a Cultivator, Urokodaki had a hidden profession: a craftsman. Whether it was carpentry or sewing, the old man was quite proficient. In contrast, his own cheapskate master was a boor who only knew how to bury his head in a bowl of food.
He naturally wanted to stay and practice these life skills. With an experienced teacher guiding him, whether it was combat arts like breathing techniques or other life skills, his efficiency would increase significantly.
Although Urokodaki didn't quite understand why the boy had suddenly lost interest in practicing breathing, he was persuaded by Kuguruma Natsunishi's reasoning.
"I wish to use the heart of a craftsman to polish the trifles of daily life, shedding the vanity of achievement and settling my own spirit."
Against such a reason, what could Urokodaki say? He could only loudly praise Kuguruma Natsunishi for his pure nature and upright heart. The two boys, of course, raised both hands in agreement.
Kuguruma Natsunishi's second request was to have a personal sparring match with Urokodaki. The old man initially wanted to decline citing his old age, but he couldn't withstand the burning fighting spirit in the youth's eyes and eventually agreed.
The match ended in Kuguruma Natsunishi's "narrow defeat."
He knew full well that Urokodaki, as a former Water Hashira, had held back. Whether it was power, speed, or the rhythm of breathing, the old man had deliberately restrained himself within a certain limit. Even so, Kuguruma Natsunishi had given his all, pouring every bit of insight and every mastered technique into each clash, yet he still could not break through the old man's defense, which was as steady as a deep pool of water.
This was the result against someone who was aged and holding back. If that were the case, then the current nine Hashira in their prime, and the Upper Rank demons who stood above the Hashira...
With his current level and skills, Kuguruma Natsunishi estimated he wouldn't even have a chance to touch them. Indeed, dreaming of challenging the final boss right after leaving the starter village was a bit too idealistic.
However, in contrast to Kuguruma Natsunishi's clear-headed self-assessment, Sabito and Giyu, who were watching from the sidelines, were already reeling with shock. They simply... couldn't see the movements.
The sparring and guidance over the past few days had unconsciously given them an illusion: that there was no insurmountable gap between them and Kuguruma Natsunishi. He was just a bit faster, a bit stronger, his swordsmanship a bit more refined... They were opponents on the same level. Kuguruma Natsunishi was only a fraction better than them. If they worked harder or teamed up as "two of themselves," they might turn the tide.
It wasn't until they witnessed his battle with Master Urokodaki that they realized how utterly wrong they were. It wasn't "a fraction better." If they met on a battlefield and had to fight to the death... Sabito and Giyu saw the same answer in each other's eyes: they probably wouldn't be able to block a single strike. They would likely be cut down in the first encounter.
"Sabito, you are much weaker than him. (And I, who am even weaker than you, don't even need to be mentioned.)"
Giyu's voice was very soft, yet it was exceptionally clear in the silent air.
Sabito did not deny it. He broke out of his brief daze, a calm and burning light gradually gathering in his eyes.
"Yes, Senpai is much stronger than we are now." He turned to look at Giyu. "That's why we must work harder and chase him even more desperately. Only then can we stand by his side in the future instead of just looking at his back."
Giyu stared at his friend. This peach-haired boy, who was always serious, gentle, and cheerful, was like a steady and warm rock always standing by his side—dispelling confusion and giving him the courage to step forward. Even facing such a massive gap in strength, Sabito would not lose heart. It was as if in his eyes, all difficulties were merely steps that needed to be climbed.
Giyu couldn't imagine what his world and life would be like if one day Sabito was no longer there. But then, Sabito was so strong; the one likely to encounter an accident would probably be himself, the weaker and less expressive "younger brother."
His gaze involuntarily drifted toward Kuguruma Natsunishi, who was preparing dinner not far away. The firelight outlined the youth's focused profile, his movements crisp and neat.
Keep up with Kuguruma Natsunishi-senpai's pace, huh?
Giyu couldn't help but imagine a scene where the three of them fought side-by-side against powerful demons in the future. He lowered his head, and in a corner no one could see, his mouth curved slightly. The future no longer seemed so bleak.
A few days later.
Kuguruma Natsunishi had just leveled his [Sewing] skill to Lv.1. A member of the Kakushi arrived at Mt. Sagiri amidst the noisy chattering of a crow. They brought Kuguruma Natsunishi's uniform along with his first mission as a Demon Slayer.
"Kuguruma Natsunishi! Head southeast! To the Village of Rain! Caw!"
"Hunt the demon! This is your first job! Caw!"
It was the black bird that called itself "Shiro" (White).
The Kakushi member below said helplessly, "Little Bai, wait until I finish explaining everything, okay?"
"Caw! Quick! Faster!"
Amidst the rustle of feathers, the Kakushi member bowed to the group at Mt. Sagiri and then took two items from the pack on his back: the black, high-collared Demon Slayer uniform and an unsheathed Nichirin Sword.
Kuguruma Natsunishi asked in confusion, "Didn't I ask for the stone I won to be made into a katar? Why is this a katana?"
The Kakushi member hurriedly explained, "Mr. Mutsu, the structure of the Nichirin Sword you requested is somewhat... novel. The smiths had many discussions about how to make that weapon. Since a plan hasn't been decided yet, we have to trouble you to use a standard-issue Nichirin Sword for now. The smiths also said that once they reach a conclusion, they would like to invite you to the Swordsmith Village for a consultation."
Is customizing a weapon really this troublesome?
Amidst his disappointment, Kuguruma Natsunishi picked up the Nichirin Sword. He drew the blade from its scabbard, looking at the brand-new edge fresh from the forge.
"Hm? It changed color?"
Kuguruma Natsunishi looked at the Kakushi in surprise. Did this sword have some kind of quality issue?!
Seeming to sense Kuguruma Natsunishi's confusion, Urokodaki spoke up to explain on behalf of the Kakushi.
"Nichirin Swords are also known as 'Color-Changing Katanas.' This is due to the special nature of the raw materials. Scarlet Crimson Iron Sand and Scarlet Crimson Ore are special ores that have absorbed a massive amount of sunlight. While they have the effect of slaying demons, they also possess other magical characteristics. For instance, right now, the blade will change into a unique color based on its first master."
Does that mean rocks that absorb sunlight turn into flashy colors like red, yellow, blue, or green? What is this, the prism effect?
The Kakushi nearby also said, "Our Kakushi division has long heard of a swordsman as powerful as Mr. Kuguruma Natsunishi. If it's Wind Breathing, it will surely be an emerald green. However, it might also be blue, like your hair..."
And then his words got stuck in his throat.
Because the blade of Kuguruma Natsunishi's Nichirin Sword was currently rippling with a mesmerizing halo, as if it were being dyed. Initially, it was a pale metallic base color, but it quickly plated over with a layer of lake-like azure. Yet, before that azure could fill the blade, layers of crimson patterns began to separate from the edges of the blue... followed by orange, golden-yellow... various glows intertwined and blurred like oil drops in water.
In just a few seconds, Kuguruma Natsunishi's Nichirin Sword displayed an extremely complex mixed iridescent color. It looked as if it had been sprayed with a layer of gasoline, shimmering with a "multicolored black" under the sun.
Forget Kuguruma Natsunishi himself; even the Kakushi, who handled swords year-round, and Urokodaki, who had taught for decades, had never seen such a situation.
Is the color of this sword a bit ugly? Can I return it?
Just as Kuguruma Natsunishi was thinking this, the "gradient gasoline" on the blade began to fade slowly, eventually returning to its original color.
"No, the color is different," Urokodaki said, pointing at the blade. "It's much brighter than before."
The original Nichirin Sword was a solid metallic grey, with deep blue patterns from the tempering visible on the side. Now, the blade had turned into a clear, bright silver-white. The marks of the hamon on both sides were not covered; instead, they appeared faintly within the glowing base, like starlight leaking through gaps in night clouds.
"It's a white sword," the Kakushi breathed a sigh of relief. Setting aside the unconventional, chaotic colors at the start, the final appearance was quite pure and dignified.
When held in his hand, the blade emitted a faint, clear ring, as if responding to Kuguruma Natsunishi.
After hesitating for a long while, Kuguruma Natsunishi used it to replace the oldest of his three equipped blades. Then, as if remembering something, he asked, "Speaking of which, don't katanas... have a tradition of being named?"
Urokodaki asked, "There is such a custom. What do you wish to call it?"
Kuguruma Natsunishi: 'Sandai Kangshifu.' (Master Kang the Third).
His previous swords had been named Jinmai-Kiri and Tong-Yi Maru. And the one he replaced was Tang-da-ren-gang. These names were taken directly from popular Asian instant noodle brands: Master Kang, Jinmai, Uni-President, and Soup Master.
To the unsuspecting Master Urokodaki, they sounded like the names of ancient, formidable blades from a distant land."