The Four Realms of Swordsmanship

The moon hung like a hook, and the night air carried a slight chill.

The crescent moon, hidden behind the clouds, seemed drawn in by Mu Yu and Koshiro's conversation as well, quietly creeping out from behind the dark clouds.

Looking at Mu Yu, Koshiro opened his eyes, utterly satisfied.

"Mu Yu, you did very well this time. Not only did you save Kuina's life, you also healed the long-standing wound in her heart—that her strength could never compare to a boy's. As her father, I'm deeply grateful to you!"

Mu Yu said, "Master, you're being too formal. Wasn't it only natural for me to save Kuina?"

Koshiro shook his head. "What you see as natural is your part. My gratitude is a father's part."

Mu Yu immediately smiled. His master had changed a great deal too!

"Although the Asura Fruit ultimately went full circle and returned to Kuina, you have left me with no regrets. Mu Yu, thank you!"

Just as Mu Yu was about to say something, Koshiro stopped him.

"Mu Yu, there is no need to be modest. You are even more outstanding than I imagined. You completed the task I entrusted to you admirably, and you protected the dojo well!"

Mu Yu said, "Not really. Terukawa even smashed the dojo's signboard!"

"A dojo's signboard has never been just a plaque. Mu Yu, you have passed every test I set for you with flying colors. I'll give you this calligraphy as a gift!"

As Koshiro spoke, he took a sheet of slightly yellowed but exceptionally well-preserved paper from his sleeve.

When Mu Yu unfolded it, four bold, vigorous characters leapt into view—Menkyo Kaiden.

A dojo had its own standards for judging a disciple's level.

"Paper Cutting" was the initial rank, a title for beginners;

"Catalogue" was the second rank, representing the names of techniques learned through training;

"License" meant one had earned the qualification to tell others the name of the school one studied, signifying that one could graduate from the master;

"Full Transmission" meant one had inherited all the techniques of that school, representing the school's most outstanding disciple, someone capable of bringing glory to the family name;

As for "Menkyo Kaiden," it was an even rarer rank. It meant that, without needing the school's approval, one could pass the school's techniques on to others.

It represented the right to take disciples independently!

Mu Yu had not expected Koshiro to give him these four words. This represented a master's highest recognition of a disciple.

The paper had already yellowed, so it must have been quite old. There might even be another story behind it!

Seeing Mu Yu's stunned expression, Koshiro smiled with satisfaction.

His disciple was truly clever to a frightening degree. Being the master of such a genius was the greatest honor of his life.

Of course, there were inevitably plenty of moments of frustration too!

When a disciple was too smart, there was often nothing left for the master to teach. As for a sense of accomplishment, there was even less to speak of!

Koshiro said, "Mu Yu, my master passed this calligraphy down to me. Now, I pass it down to you."

This calligraphy had been passed down to Koshiro by his master?

Mu Yu was greatly startled, and suddenly felt the sheet in his hands grow heavy.

After thinking for a moment, Mu Yu carefully folded the paper again and tucked it away close to his body.

Seeing Mu Yu treasure the calligraphy so dearly, Koshiro immediately felt a heavy weight lift from his heart.

Koshiro said, "Mu Yu, I originally had not intended to tell you these things so soon, but you have proven even more outstanding than I expected. I might as well tell you everything at once!"

Mu Yu was puzzled. What did Koshiro intend to tell him?

"Mu Yu, receiving the title of Menkyo Kaiden means that you have learned every technique of Isshin Dojo. But the world is vast. With your current swordsmanship, among all swordsmen, you can probably only be considered average!"

"Average?"

Mu Yu was not too surprised. After all, the high-level fighters in the world of One Piece were genuinely capable of destroying heaven and earth.

During the Marineford War, Whitebeard casually caused massive earthquakes and tsunamis, leaving the Marine headquarters at Marineford in utter ruin.

With a single move, Ice Age, Admiral Aokiji could freeze an entire stretch of sea!

As for Hawk Eyes, the World's Greatest Swordsman, he treated normal attacks like ultimate moves. A casual slash from him could send sword energy tearing across hundreds of meters.

His little bit of strength really amounted to nothing in the world of One Piece.

What Mu Yu was curious about, however, was how Koshiro had judged his level of strength.

Seeing Mu Yu's puzzled expression, Koshiro smiled even more happily. At last, he had encountered an area Mu Yu did not understand.

Being this kid's master was too hard!

"Yes. In my understanding, swordsmanship can actually be divided into four realms:"

"The first realm is treating the sword as a weapon for combat, simply knowing some sword techniques. Kuina and Zoro are currently in this realm."

"The second realm is the union of swordsmanship and will, comprehending one's own [Way]. Mu Yu, your Wisdom King is the Way in your heart. In this realm, a swordsman can easily cut through steel."

"The third realm is the union of swordsmanship and Haki. Haki is easy to obtain, but a Way is hard to seek. That is why I never told you about methods for training Haki before—I was afraid you would aim too high. By using Haki, one can temporarily turn a sword into a 'black blade,' greatly increasing its power."

As Koshiro spoke, he snapped off a branch from the courtyard.

"The technique of coating a weapon with Armament Haki is also called [Ryuo] in my homeland. Mu Yu, watch."

Perhaps because he was deliberately demonstrating it for Mu Yu, Koshiro coated the branch with Armament Haki very slowly. Mu Yu could even see the Haki gradually spreading over the branch.

"Haki is power hidden within the human body. Ordinary people cannot use it; it requires long periods of training and guidance. The sensation is roughly like your skin heating up and burning from the inside out. It first turns orange-red, then transitions into a bright black with a metallic sheen."

Clang!

With a sharp sound, Mu Yu's fist first turned orange-red before transitioning to jet black.

"Master, like this?"

Thud!

Koshiro's squinty eyes suddenly widened, and his eyeballs nearly popped his glasses right off his face.

What the hell was this?

Even talent had to have a limit, didn't it?

Koshiro felt as if his mindset was collapsing!

Seeing Koshiro lose his composure, Mu Yu could not help smiling.

"Master, thank you for your guidance. Actually, when I fought Terukawa, I had already comprehended Observation Haki. Then my Devil Fruit ability allowed me to learn Armament Haki and Conqueror's Haki!"

What?

Koshiro felt the urge to cough up blood.

What kind of ridiculous Devil Fruit was this Tree Planting Fruit?

It could even indirectly teach someone Haki?

Even more outrageous, Conqueror's Haki was no exception!

Mu Yu smiled, thoroughly amused by Koshiro's loss of composure.

Still, Koshiro was a Great Sword Master after all, and his mental fortitude was quite good. He adjusted himself in an instant.

With a solemn expression, Koshiro said, "Mu Yu, your Devil Fruit ability is very powerful, but as a swordsman, you must not rely on your fruit too heavily. Strength of heart is true strength."

Mu Yu said, "Yes."

Koshiro nodded. "The fourth realm is 'tempering the blade through countless battles.' It is the process of making a sword permanently become a true 'black blade.' In my homeland, there is a national treasure called Black Blade Shusui, forged over a lifetime by the Great Sword Master Ryuma."

"A black blade is also called a 'meritless blade' or an 'unsharpened blade.' It may not be especially sharp, but it is incomparably tough. Only a true Great Sword Master can forge one. Black Blade Shusui is so tough that even if a dinosaur stepped on it, it would not bend by a single millimeter."

Hearing Koshiro's explanation, Mu Yu could not help but feel his heart stir with yearning.

Forging a true black blade—perhaps that was the so-called path of the sword master!

"Mu Yu, come with me!"

"Yes."

Although Mu Yu was puzzled, he still followed behind Koshiro.