Daily Training and Mastering the Prototype of "Blue"

After completing their mission in Wisteria Town, Moyu and Tanjiro safely escorted the surviving girl home and reported what had happened to the Demon Slayer Corps Headquarters through a Kasugai Crow. The girl's family thanked them profusely, but the deaths of the other two missing girls still weighed heavily on Tanjiro. It strengthened his resolve to grow stronger, slay more demons, and protect the innocent.

In the days that followed, neither of them received new mission orders right away. According to the information brought by the Kasugai Crow, demons seemed to have become more secretive in their activities lately. The relative peace gave Moyu and Tanjiro a chance to consolidate their gains and improve.

Morning mist still lingered over Mount Sagiri. But in the clearing before the cabin, the atmosphere of their training was a little different from before.

Tanjiro focused mainly on two things: further refining the ten forms of Water Breathing until they flowed together more smoothly, and exploring how to combine his family's Hinokami Kagura with a Breathing Style. Often, in the quiet of the night, he danced beneath the moonlight. With every swing, the dark red sheen on his blade grew more distinct, and the temperature around him rose subtly. Nezuko always sat quietly on a large rock nearby, her chin in her hands and her wide eyes fixed on her brother as he trained. Whenever Tanjiro made a breakthrough and a more substantial phantom of flame sprang up along his blade, she happily swung her little feet and encouraged him with muffled "Mmm! Mmm!" sounds.

Moyu, meanwhile, focused entirely on consolidating the gains from the Six Eyes' "growth stage" and trying to gain rudimentary control over that dangerous, powerful force—the prototype of Blue.

After accumulating rewards from the final selection on Mount Fujikasane and the mission in Wisteria Town, he had a considerable reserve of gold coins. Without hesitation, he spent 5,000 of them at the system shop to redeem the Mental Strength Meditation Method he had unlocked earlier.

[Redemption successful: Mental Strength Meditation Method]

[Effects: Greatly increases maximum Mental Energy and recovery speed, enhances the ability to process complex information, significantly reduces the risk of information overload from the Six Eyes, and lays the foundation for controlling advanced abilities.]

This meditation method was more than simply sitting still and regulating one's breathing. It contained a complex set of mental visualization and energy-ordering techniques. With the aid of the Six Eyes, Moyu could clearly look inward at his own sea of consciousness. He gradually sorted and organized the once chaotic torrent of information, building a stronger, more resilient mental barrier.

The effects of several days of meditation training were immediate. The most obvious improvement was that his headaches became far less frequent and severe. Even with the Six Eyes active for long periods, he could keep a clear head. At the same time, his perception and control of the Breathing Cursed Energy within him, which fused a Breathing Style with a trace of Cursed Energy, became more refined.

"Time to try again..." Moyu took a deep breath and walked over to the enormous rock he usually used for practicing his slashes. It was far larger and harder than the ones he had cut through during his earlier training.

He closed his eyes and concentrated intensely, visualizing the principle behind Blue—compressing the space between two points infinitely to create a "negative infinity" singularity that attracted everything. This time, he was consciously guiding it rather than acting on instinct.

The Six Eyes operated at full capacity, and the structure of the space around him grew clear to his senses. He slowly raised his right hand, palm forward, and Breathing Cursed Energy began gathering toward it along an extraordinarily complex and precise path. This was not a brute-force infusion, but the construction of a temporary, miniature framework for manipulating space. Like the finest carving tool, his Mental Energy guided the Cursed Energy in tracing out an invisible Cursed Technique.

The process was extraordinarily difficult. The slightest deviation in the energy could cause the framework to collapse or even backfire. Fine beads of sweat formed on Moyu's forehead, and his temples throbbed slightly, but with the powerful control granted by the Mental Strength Meditation Method, he barely managed to keep the framework stable.

Gradually, the space an inch in front of his palm began to distort visibly. The air seemed to be drawn into an invisible point, and light bent along with it. An exceedingly tiny black sphere, no bigger than a grain of rice, slowly appeared.

It was the prototype of Blue!

Unlike the fist-sized black sphere that had radiated terrifying suction when it went out of control last time, this grain-sized Blue looked extremely unstable. Its edges were blurred, as though it might vanish at any moment. But Moyu had indeed succeeded in creating it!

However, maintaining it required an astonishing amount of Mental Energy and Cursed Energy. Moyu could feel both his Mental Energy and physical strength draining away rapidly, like floodwaters surging through open gates.

He dared not delay. He immediately fixed his mind on the enormous rock ahead, targeting a point at its center.

"Go!"

Driven by his will, the grain-sized black sphere trembled slightly, then turned into an almost invisible black thread and vanished into the rock in an instant.

There was no sound, no explosion.

The next second, a grating creak came from inside the enormous rock, as though something were being forcibly crushed. Countless spiderweb-like cracks suddenly appeared on its surface, centered on that point, and spread rapidly across the entire rock!

Immediately afterward, the entire boulder collapsed with a crash, as though an invisible giant hand had crushed it from within. It became a pile of fragments of various sizes, while the center was reduced to fine stone powder!

Drained, Moyu dropped to one knee, gasping for breath. His face was pale, but his azure-blue eyes gleamed with excitement.

Success! Although this is only the most rudimentary application, with a small range, limited power, and enormous consumption, it means I've finally set foot on the right path to mastering Blue! It's no longer a disaster that goes out of control, but a powerful move I can aim!

[Ding! Mastery of "Limitless: Blue (prototype)" increased to 5%.]

[Rewards: Gold coins +500, a slight increase in spatial perception accuracy.]

The system's notifications confirmed his progress.

"Moyu! Are you all right?" Hearing the commotion, Tanjiro hurried over and looked worriedly at the shattered rock covering the ground and the panting Moyu. Nezuko also jumped down from the big rock and ran to Moyu on her short little legs. She caught his sleeve in her small hand, her pink eyes full of concern.

"I'm fine." Having caught his breath, Moyu gave Tanjiro and Nezuko a reassuring smile. "I was just trying a new move. It left me a little drained."

Tanjiro looked at the pile of rubble and clicked his tongue. "That power... it's terrifying. Moyu, the power your eyes give you is incredible."

Moyu shook his head and said seriously, "Power itself is neither good nor bad. What matters is how you use it. This power is dangerous. I have to master it completely before I can use it to protect the people I want to protect, rather than cause destruction." As he spoke, he looked warmly at Nezuko, who was gently patting his arm with her little hand to help him catch his breath.

Nezuko seemed to understand. She nodded vigorously, then took a berry wrapped in a clean leaf from her little apron pocket and held it up to Moyu's mouth. "Mmm!" she said, gesturing for him to eat it and regain his strength.

Moyu paused, looking at the pure, innocent kindness in Nezuko's eyes as warmth welled up inside him. He took the berry and said softly, "Thank you, Nezuko."

Nezuko immediately narrowed her eyes in delight, as though she had completed some important task.

In the days that followed, Moyu settled into a regular routine. In the mornings, he sparred with Tanjiro and exchanged pointers on Water Breathing. He also shared some techniques for applying force and little tricks for using energy that he had observed with the Six Eyes, helping Tanjiro improve his movements and efficiency. Tanjiro progressed quickly as well. In particular, after incorporating the rhythm of Hinokami Kagura into his breathing, his slashes increasingly gained a searing explosive force.

In the afternoons, Moyu focused on the Mental Strength Meditation Method and practicing control over Blue. He no longer pursued power, instead concentrating on reducing its cost and improving its stability and precision. At first, he could only create a grain-sized Blue that lasted an instant. Gradually, he became able to make one the size of a soybean and maintain it for three seconds, while controlling its point of impact and range of attraction more precisely. Although it was still some way from being usable in actual combat, his progress was clear every day.

Nezuko was undoubtedly the warmest part of their training life. She could not speak, but she showed her affection and reliance on her brother and Moyu through her actions. She helped Tanjiro gather scattered firewood and stack it, though the piles were often crooked, and brought Moyu fresh water or wild fruit as soon as he finished meditating. She was especially fond of the faint azure-blue glow of Breathing Cursed Energy that flowed around Moyu when he trained, and she often watched it in fascination. Sometimes she even unconsciously copied Moyu's breathing rhythm. Although she did not need to breathe as a demon, this strange synchronization seemed to make her feel comfortable.

Occasionally, Sakonji Urokodaki also appeared to offer guidance. The former Water Hashira had a discerning eye and could always pinpoint the shortcomings in their training. Although Urokodaki could not directly guide Moyu in his use of Blue, which involved the power of space, he warned him to proceed step by step and not rush. The foundation of power lay in a solid physique and a resilient will.

Peaceful days always passed quickly. About half a month later, the Kasugai Crow brought another mission.

"Caw! Northwest, fifty li away, Maple Leaf Town! Suspected demon activity! Several people returning home late have been attacked, with unusual wounds! Mizunoto-ranked members Moyu and Tanjiro Kamado are ordered to investigate! Caw!"

The arrival of a new mission meant the start of a new journey. Moyu and Tanjiro checked their equipment, and Tanjiro shouldered the wooden box carrying Nezuko.

"Maple Leaf Town... it sounds like a beautiful place." Tanjiro looked northwest, his eyes grave at the prospect of encountering a demon, yet resolute in his determination to protect innocent people.

"Mm." Moyu nodded and gently touched Azure Star at his waist. Beneath the cool sheath was a blade eager for action. "Let's go."