The Seeds of a Unique Form

On the third day after cutting through the second boulder, Moyu finally had time to settle down and examine the preview access to the system's intermediate exchange section.

Late at night, in the cabin on Mount Sagiri, Tanjiro was fast asleep, breathing evenly. Moyu sat cross-legged on his bedding, keeping his Six Eyes active at the lowest possible load as he immersed his consciousness in the system interface.

[Preview access to the intermediate exchange section activated]

[Available previews (five items selected at random):]

[1. Ice Release, beginner level (2,500 coins)]

A bloodline limit from the world of "Naruto," capable of manipulating water- and wind-nature chakra to form ice. Compatibility advice: may resonate with Water Breathing, but beware of energy conflicts.

[2. Observation Haki, intermediate level (3,000 coins)]

From the world of "One Piece." It could sense the presence of living beings, predict their actions, and even hear their thoughts. Compatibility advice: combining it with the Six Eyes could create "all-domain perception," but would consume an enormous amount of mental energy.

[3. Zanpakuto: Asauchi (3,500 coins)]

From the world of "Bleach," a Zanpakuto that had not yet undergone its initial release. It could gradually awaken according to the characteristics of its wielder's soul. Compatibility advice: potential compatibility issues with this world's Nichirin Blade system; choose with caution.

[4. Nen Ability: The Four Fundamental Principles (2,000 coins)]

From the world of "Hunter × Hunter," the four foundations of the life energy known as Nen: Ten, Zetsu, Ren, and Hatsu. Compatibility advice: highly compatible with the breathing Cursed Energy system and could serve as a supplementary system.

[5. Sharingan: One Tomoe (4,000 coins)]

From the world of "Naruto," it provided the foundations of perception, copying, and genjutsu. Compatibility advice: serious risk of conflict with the Six Eyes; possessing both was not recommended.

Moyu carefully read each description, weighing his options. None of them were cheap. His current savings—even with his reward, he had only 1,800 coins—fell far short. But more important were compatibility and potential for future development.

System, based on my current circumstances, which exchange should I prioritize? he asked inwardly.

[Analyzing... Recommendation: Nen Ability: The Four Fundamental Principles]

[Reason: like this world's Breathing Styles, it is a system for developing life energy, with 85% compatibility. Among the Four Major Principles, Ten can strengthen defense, Zetsu can reduce the load on the Six Eyes, Ren can increase explosive power, and Hatsu can serve as a foundation for developing a unique form.]

[Note: after fully mastering the Four Major Principles, the host can awaken a unique Nen ability based on their characteristics.]

Nen? Moyu fell into thought. Breathing Styles and Nen were indeed both applications of life energy, so in theory they should blend well. The price was relatively low, too. If he saved up, he should be able to exchange for it before the Final Selection.

But he did not decide immediately. His exclusive task, "Create a unique Breathing Style," was still in progress, and he wanted to see how far he could get on his own first.

Closing the system interface, Moyu stepped out of the cabin. Mount Sagiri was silent in the dead of night, save for the chirping of insects and the sound of a distant waterfall. Moonlight spilled through the forest, draping everything in a veil of silver.

He came to the third boulder—the largest one, a massive rock like a small hill. Urokodaki's final assignment for him was to cut it apart before leaving Mount Sagiri, but he had imposed even stricter conditions: Moyu was allowed only one strike, and the cut surface had to be as smooth as a mirror, without a single fragment breaking off.

It was an almost impossible task. Cutting through a boulder this massive would inevitably send fragments flying from the impact. Unless...

Moyu reached out and touched the rock's surface. Breathing Cursed Energy seeped through his palm, just as it had when he sensed the rock's "breathing" before. But this time, he had a new idea.

The "spiral force" Sabito had mentioned had inspired him. But what if he went beyond spirals? Water had countless forms—flowing water, mist, ice crystals, whirlpools, waterfalls...

Breathing Styles had "forms" to turn the intangible concept of water into tangible techniques. In that case, could breathing Cursed Energy imitate more of water's forms?

Moyu closed his eyes and began constructing ideas in his mind. The Six Eyes' computational ability ran at full power, simulating the possibilities.

First came "mist."

Mist had no form or substance, yet it could permeate everything. If he turned his breathing Cursed Energy into mist, seeped it into every crack in the rock, and then destroyed every structure inside it at once...

No, that would only pulverize the rock. It would not produce a smooth cut.

Then what about "ice"?

Water expanded as it froze, producing tremendous pressure. If he made his breathing Cursed Energy "freeze" inside the rock and force open a crack from within...

That was wrong too. It demanded too much control, and it would be hard to ensure a smooth cut.

Moyu pondered for a full two hours, rejecting dozens of ideas. Just as the horizon began to pale, an entirely new thought flashed through his mind like lightning.

What is water's strongest property?

It was neither hardness nor its ability to change form, but—incompressibility.

In a sealed space, water was almost impossible to compress and transmitted all pressure applied to it. If he could give his breathing Cursed Energy a similar property, forming an "incompressible" energy membrane inside the rock, and then apply pressure at a single point...

The pressure would be transmitted evenly across the entire area covered by the energy membrane, which would then burst apart neatly at its weakest point—the predetermined cutting plane.

Just like cutting metal with a water press.

The idea made Moyu's heart race. He immediately put it to the test, injecting a wisp of breathing Cursed Energy into the rock's surface. This time, rather than penetrating it, he "spread" the energy out, forming a thin plane inside the rock.

Then he encountered a problem. Once breathing Cursed Energy left his body, it was difficult to maintain its shape, and it soon dissipated. He needed to find a way to make the energy "remain stable."

"Your power lacks a 'framework.'"

A gentle voice came from behind him. Moyu turned and saw Makomo's soul floating in the morning mist, her translucent body flickering in and out of sight in the faint light.

"Miss Makomo?"

"Sabito and I saw what you were trying." Makomo floated over to the rock. "It's an interesting idea, but it won't work. Your energy has no 'skeleton.'"

"A skeleton?"

"Just as a house needs beams and pillars, the 'forms' of a Breathing Style are the skeleton of its energy," Makomo explained. "Each of Water Breathing's ten forms is a specific framework for circulating energy. You created Zero Form, but it's only a fledgling version. It doesn't yet have a complete framework to support it."

Understanding dawned on Moyu. His Vortex Slash was indeed only one way of using breathing Cursed Energy; it was far from a complete "form."

"Then how do I construct a framework?"

"Ask yourself." This time, it was Sabito's voice. He emerged from the woods nearby, his fox mask gleaming faintly in the morning light. "What is the essence of your power? What does the world look like through your eyes? Incorporate those answers into your breathing, and the framework will appear on its own."

Essence? The essence of the Six Eyes is insight and manipulation. The essence of breathing Cursed Energy is fusion and transformation.

Moyu sank into thought. Insight... manipulation... fusion... transformation...

Suddenly, he recalled what he had felt when he cut through the second boulder. It had not been a cut, but an "unbinding." He had gently parted it along the interface of its molecular structure.

If "insight" let him see the structure of everything, "manipulation" let him affect those structures, "fusion" let his power resonate with everything, and "transformation" let him change the nature of his power...

Then what he needed was not cutting, but "separation."

Moyu opened his eyes, a gleam of understanding flowing through his azure pupils. He pressed his hand against the rock once more and slowly injected his breathing Cursed Energy.

But this time, his aim was not destruction, but "marking."

With the Six Eyes fully activated, every molecule and every chemical bond in the rock appeared clearly in his vision. Moyu searched the structure for the interface most readily separated—not a weak point, but a natural "dividing line."

He found it. It was a thin layer composed of different minerals, running almost perfectly horizontally through the entire rock.

His breathing Cursed Energy spread along the interface, forming an extremely thin energy net. Moyu controlled it with care, making the net "vibrate in resonance" with the rock's molecular structure, their frequencies gradually synchronizing.

This was not opposition, but resonance. Once the resonance reached perfection, the rock would "think" the interface was meant to come apart.

The entire process took a full fifteen minutes. Cold sweat beaded on Moyu's forehead as his mental energy drained at an astonishing rate. But the Six Eyes and breathing Cursed Energy worked together more and more smoothly, as though they had always been one.

At last, the energy net completely covered the intended cutting plane.

Moyu stepped back three paces and drew his Nichirin Blade. He did not assume the opening stance of any form, but merely touched the tip of his blade lightly to the rock's surface, right at the center of the energy net.

"Water Breathing, Zero Form, Second Form: Mirror-Surface Unbinding—"

He softly spoke the name he had given it:

"—Mirror Dissection."

The blade tip trembled slightly, transmitting a strange vibration through the blade and into the energy net. The entire net began to vibrate in unison, its frequency perfectly matching the rock's molecular structure.

Without a sound, the rock slowly slid apart along the interface. The cut surface was as smooth as a mirror, clearly reflecting Moyu's pale face and the sun just rising in the sky. There were no fragments and no thunderous crash. It was like a heavy book being gently opened.

Done.

Moyu dropped to one knee, bracing his Nichirin Blade against the ground as he gasped for breath. The technique had exhausted nearly all his mental energy, but an unprecedented sense of accomplishment welled up inside him.

This was not brute-force destruction, but intricate manipulation. Not cutting, but separation.

[Ding! Original Breathing Style forms completed: 2/3]

[Zero Form, Second Form: Mirror-Surface Unbinding, "Mirror Dissection," registered in the system]

[Effect: can separate nonliving matter without damage, with molecular-level precision]

[Cost: three times the mental energy of a standard form]

[Reward: coins ×800; knowledge transfer unlocked: Energy Stabilization Framework Construction Method]

The system notifications arrived as promised, and at the same time, knowledge of energy framework construction flooded his mind. Moyu closed his eyes to absorb it, finally understanding what Makomo had meant by a "skeleton."

Every Breathing Style form had an internal energy circuit, much like a circuit diagram. His previous attempts had been nothing more than haphazard wiring; only now had he truly learned to draw a design.

"Remarkable."

Urokodaki's voice came from behind him. Moyu turned and saw that his teacher had appeared nearby at some point, his Tengu Mask facing the mirror-smooth cut surface.

"This technique has already gone beyond the scope of a 'form.'" Urokodaki walked up to the cut rock and ran his fingers over the mirrorlike surface. "No destruction, only separation... That is the principle behind healing techniques, yet you applied it to a strike."

Moyu struggled to his feet. "I still need to refine it. The cost is too high, so it's hard to use in actual combat."

"That is why you must continue training." Urokodaki turned around. "Your Third Style should solve the problem of its cost. Before the Final Selection, you must complete all three styles and create a complete system."

"Yes, sir."

"One more thing," Urokodaki said after a pause. "Help Tanjiro out more, too. His path is different from yours, but you can test your insights against each other's."

Moyu nodded. At that moment, Tanjiro also came running to the training ground. His eyes went round when he saw the enormous rock cut in two.

"M-Moyu! Did you really cut that apart?!"

"I separated it," Moyu corrected him. "Tanjiro, how is your rock training going?"

Tanjiro scratched his head. "I'm making progress, but I still have a long way to go." He looked at the neatly divided boulder, both envy and fighting spirit in his eyes. "But I'll work hard! I'm going to create my own form too!"

Over the following days, their training entered a new phase. Moyu continued refining his Zero Form in the mornings, then sparred and exchanged techniques with Tanjiro in the afternoons.

During their sparring, Moyu noticed how astonishingly fast Tanjiro was improving. Although Tanjiro had yet to cut through a rock, his Breathing Style was becoming increasingly fluid, and traces of Hinokami Kagura had begun to blend into his Water Breathing.

During one sparring session, an illusory flame briefly ignited on Tanjiro's wooden sword. Although it lasted only an instant, its heat was real.

"Tanjiro!" Moyu called a halt to their sparring. "That move just now... do it again!"

Tanjiro himself was stunned. "I-I don't know how I did it either..."

"It was the rhythm of the Kagura dance." Moyu's Six Eyes had seen it clearly. "Your breathing rhythm just now matched the Kagura dance exactly. Tanjiro, try dancing the Kagura during training, but not with your body—with your breathing."

"Dance with my breathing?"

"Let your breathing become the dance, and let the dance become your breathing."

The instruction was abstract, but Tanjiro understood. As he swung his sword, he began silently recalling the rhythm of the Kagura dance, letting his breathing rise and fall with it.

Three days later, flames ignited on Tanjiro's wooden sword again. This time, they lasted three seconds. The flames were not very hot, but they contained a kind of burning spiritual will.

"This is..." Urokodaki had appeared at the edge of the training ground at some point. "The beginnings of Sun Breathing."

"Sun Breathing?" Tanjiro was bewildered.

"The oldest Breathing Style, and the source of all other Breathing Styles." A rare note of emotion entered Urokodaki's voice. "I thought it had been lost... Tanjiro, has your family performed rituals centered on fire for generations?"

Tanjiro nodded. "Yes! The Kamado family sells charcoal, but we're also responsible for worshipping Lord Fire God. The Kagura dance is part of the ritual..."

"Then there's no mistake," Urokodaki said. "Keep following this path. But remember, until you have mastered it completely, do not use these flames in front of anyone else in the Demon Slayer Corps. Sun Breathing... is connected to too many secrets of the past."

Tanjiro only half understood, but he solemnly agreed.

That night, Moyu saw the souls of Sabito and Makomo again. They brought new information.

"The disturbance on Mount Fujikasane has grown worse." Sabito's tone was grave. "We can sense the resentment gathering there growing stronger and stronger. Powerful demons are actively hunting the swordsmen taking part in the selection, not out of hunger, but for... pleasure."

Makomo added, "And there's more than one. At least three demons have auras far stronger than ordinary ones. They seem to be competing to see who can kill more people."

Moyu's heart sank. This had not happened in the original story. Clearly, the world line had changed because of his arrival.

"We'll keep watching," Sabito said. "But you need to be prepared. The Final Selection could turn into hell."

After seeing the two souls off, Moyu opened the system interface. His coins had accumulated to 2,600, leaving him just 400 short of exchanging for Nen Ability: The Four Fundamental Principles.

But he was in no hurry to exchange for it. His exclusive task needed only one last form, and he had to finish that first.

The Third Style had to solve the problem of its cost.

Moyu considered the possibilities. There were only a few ways to reduce the cost: improve energy efficiency, draw on an outside force, or... give the technique itself the ability to "grow."

Growth?

A bold idea took shape in his mind.

What if the technique was not fixed, but could "evolve" according to the situation? What if he could create a "living" form that improved and optimized itself through use...

The idea was far ahead of its time, but Moyu decided to try. He had the Six Eyes, the system's assistance, and the unique properties of breathing Cursed Energy.

Night grew late, but Moyu remained in front of the rock, deep in thought. In the moonlight, his shadow stretched long.

In the distance, Tanjiro was also doing extra training, the sound of his wooden sword cutting through the air unceasing.

Farther away, Sakonji Urokodaki stood outside his house, gazing at the starry sky. No one knew what he was thinking.