Many women in the Nine Snakes Pirates let out ear-piercing screams.
They looked at Kai with expressions as if they were staring at a monster.
Learning to dominate and harden so quickly left them feeling incredulous and amazed.
Releasing it externally?
That was a high-level Armament Haki technique. Only one person in the entire Kuja Pirates could use it, and that was the Pirate Empress, Boa Hancock.
"I see."
At that moment, Shisui wore a look of surprise on his face.
He wrapped Armament Haki around his arm, clenched his fist tightly, and then struck a target in the distance.
Crack!
Barrels exploded in the distance.
"Again!!!"
Kai looked at Uchiha Itachi and asked, "Itachi, do you know how to do it?"
Uchiha Itachi nodded. "I learned."
Uchiha Itachi then demonstrated the technique just like Kai and Shisui had done.
"…"
Everyone in the Nine Snakes Pirates was left speechless. They felt as if their understanding of the world had been turned upside down.
They felt like they were going crazy. What was happening? When did Haki become so easy to learn? Or were they approaching the learning of Haki all wrong?
Hancock stared at Kai in disbelief and said, "You really... have never studied Haki?"
"Of course not. If I had, why would I ask you for advice?"
"Then how could you learn Haki so quickly and use its advanced techniques? This is definitely not something beginners can master."
If she had never learned it before, she would never believe that someone could grasp Haki so quickly. The reason was simple: she hadn't learned Haki that fast. She was like a queen; how could anyone be faster than her? She refused to admit that she was inferior.
Kai smiled and explained, "Although we don't know Haki, we do know Ninjutsu. To release Ninjutsu, we need to extract Chakra from our bodies. Chakra is the product of the perfect fusion of physical and mental energy."
"Armament Haki, from our perspective, is simply the energy generated by the transformation of physical energy. Chakra has seven properties: water, fire, wind, lightning, earth, yin, and yang, while Armament Haki has only a single property, making it easier to learn."
Although everyone in the Nine Snakes crew was a bit confused by what Kai was saying, they understood the general idea. The energy they cultivated was more advanced, and the skills were more complex.
Armament Haki was too easy for them.
They didn't realize that while Armament Haki seemed simple, mastering it was not something that could be achieved so quickly. The real reason was that all three of them were extraordinary geniuses.
"…"
"But while Armament Haki is relatively simple, the simpler something is, the more powerful it can be. I truly admire those who created Haki."
Some things may seem straightforward, but the hardest part is breaking through from zero to one. They were just beginning to learn.
Uh-huh!
Kai's entire body was covered in armor and hardened.
He moved his body and felt that his movements were slightly restricted, but it was within an acceptable range.
Moreover, there was no need to harden his entire body. Not only was it inconvenient for movement, but it was also a waste of energy.
Kai focused on selectively hardening different parts of his body—sometimes his arms, sometimes his head, and sometimes his feet—reacting with remarkable speed.
Here's the revised version of your text with "Xuanyan" replaced by "Kai," along with grammatical corrections and adjustments for an American English style:
Kai then pulled out his Nichirin Sword, specially crafted in the swordsmith village from Demon Slayer: Kimetsu no Yaiba. This village has been passed down for thousands of years, and its sword-making skills are considered to be at the pinnacle.
Kai's blade was black, the same color as those of Kamado Tanjiro and Ubuyashiki Enichi.
Wrapping his Nichirin sword in Armament Haki, the black blade became even darker and shinier, as if coated with a layer of glaze.
Kai swung his sword with force.
Whoosh—!
A massive black slash erupted from Kai's sword, cutting through the air and heading straight for the sea.
Boom—!
The ocean in front of him seemed to be cleaved in half by Kai's slash, splitting apart as waves surged to either side. After a moment, the churning waters rushed back to fill the ravine.
"Good."
Seeing the power of his attack, Kai nodded in satisfaction.
With the enhancement of Armament Haki, the strength of his slashes was elevated to a new level, and he no longer had to worry about his sword not being able to withstand his own power.
Shisui and Itachi were also practicing alongside Kai, becoming increasingly proficient in their use of Armament Haki. They could effortlessly perform full-body hardening, partial hardening, and even attach Haki to their weapons.
The women of the Nine Snakes were left dumbfounded. They began to doubt whether they and the newcomers had learned the same techniques.
Marigold, who was responsible for teaching Kai, was at a loss for words. She had only been training for a short while, and the level of Kai's Armament Haki had far surpassed her own, delivering a significant blow to her self-esteem.
"Is this... a genius?"
Ryudan, the sniper of the Nine Snakes Pirates, couldn't help but admire the fact that Kai had surpassed all their years of hard work in such a short time.
They were the elite warriors selected from many on Kuja Island, the strongest of the strong, allowed to join the Kuja Pirates.
But in comparison to Kai, Shisui, and Itachi, they began to understand what true genius really meant.