The time that I have been waiting for!

"Are you really going to the Dressrosa Kingdom?" 

Part of her was surprised by how impressive Shinra's learning ability was since he quickly mastered all the special martial arts of the World Government, Rokushiki. 

Geppo, Tekkai, Rankyaku, Soru, Shigan, and Kami-e. 

All of those six, which were the keys of the Rokushi, were mastered by Shinra in just a single day, including the Seimei Kikan, or the Life Return, a martial art that made him able to control every part of his body perfectly, increasing his metabolism, recovery, or simply manipulating his body at will. 

Nevertheless, Shinra had to say that despite the simplicity of the Rokushiki, this martial art was quite nice. 

Geppo allows users to push themselves off the air itself with superhumanly strong kicks, allowing them to travel through and remain in midair for an extended period of time.

Tekkai hardens the users' muscles to the level of iron, an effect that seems to extend to their skin, greatly boosting their physical durability.

Rankyaku is a powerful projectile technique in which the user starts by kicking at very high speeds and strength, which results in a sharp compressed blade of wind or "Sickle Wind" that can slice through objects and greatly damage a human body.

Soru allows the users to move at extremely high speeds in order to avoid attacks, as well as to attack at higher speeds and with greater power. 

Shigan is a close-quarter combat technique in which the user uses their finger to pierce the target's flesh at a very high speed.

Kami-e allows users to relax their body and make it take on the characteristics of a piece of paper; this grants the user extraordinary flexibility that allows them to avoid any attacks. 

Lastly, there is even the last secret technique known as Rokugan that is similar to the one-inch punch. 

That said, while those martial arts were simple, some were more or less similar to some martial arts in the world of Kengan, such as Shigan, which was a finger stab similar to the Devil Lance used by Kuroki Gensai, an attack that Shinra often used, but as the world of One Piece had crazy physical ability, those martial arts could send powerful compressed air attack, which made him able to attack from a distance. 

Even though the improvement wasn't much, as Shinra mastered the Rokushiki, he knew that the destruction caused by his martial arts was further enhanced. 

At the same time, there was also Haki, and since the World Government had been in control of this world for 800 years, it was natural for them to be able to gather all the knowledge of the possibilities that Haki could do. 

Armament Haki, besides covering the user's body with invisible armor, provides incredible offensive and defensive capabilities by manipulating the life-force. It also allowed them to harden their bodies or imbue their weapons or attacks with it, such as Shinra with his blade. 

Still, this was far from the end since in the advanced development, which is known as emission and internal destruction. 

Outside and inside. 

The emission allows the user to let the Armament Haki flow out from a part of their body (usually their hand) and emit it over a short distance without a medium to carry it. This allows the user to unleash a small invisible burst, which will knock back anything in the aforementioned body part's immediate vicinity with the force of a very powerful punch. Thus, the user becomes capable of striking and harming people and objects without making physical contact with them.

Internal Destruction enables the user to infuse the Armament Haki into a target's body, causing it to be destroyed from the inside out. This can be achieved by touching, grabbing, or even emitting Haki towards the object. 

Yes, they might be simple, but Shinra felt that he had grown stronger, though Stussy was speechless at how easily he was able to master all of them. 

Yet, even though the Armament Haki was easy for him to master, the Observation Haki was different, as they were more complex. 

Still, while the Armament Haki was for attack and defence, the Observation Haki was akin to that of a support, as the master of this ability allowed them to gain an extrasensory sixth sense that enabled them to sense the presence of others. 

If one wanted to develop it further, then there were several paths known as strength sensing, which made one able to gauge the strength of others; emotion sensing, which made one able to tell the emotions of others; and intent sensing, which made one able to sense another person's intent to act. 

If one mastered this ability, could they even see the future, hide their presence, read minds, or use hypnosis? 

He wasn't sure, but thought that the mastery of the Observation Haki was limited, so there was still much room for development. 

As for the last type of Haki, the Supreme King Haki, Shinra only knew that it was a Haki that allowed others to dominate others, which would incapacitate others, making them pass out or weaken with just their aura alone. 

To develop it further, it was to infuse the Supreme King's Haki into the attack. 

Then again, the development of the Supreme King Haki was similar to that of Observation Haki, as only one among millions possessed this ability, and its development was extremely limited. 

Regardless, while the Devil Fruits were amazing, the power of the Haki and the martial arts couldn't be forgotten. 

Yet, no matter how complicated and complex the future developments of those abilities, the foundation, basics, and simplicity were sometimes the keys. 

As Bruce Lee said, "I fear not the man who has practiced 10,000 kicks once, but I fear the man who has practiced one kick 10,000 times." 

Then again, no matter how amazing the abilities were, in the end, the core of everything was energy, but fortunately, he had eaten the Batto Batto no Mi, Model: Vampire, so if he needed energy, he could use the blood of his enemies. 

Still, even so, Shinra continued to train in everything, whether it was the Observation Haki, Armament Haki, or even the Supreme King Haki. His training was so brutal that his women were worried about him, yet they knew that his battle would be different from others, and if a battle happened, then if he lost, he would die, and because of that, he had to give his all. 

'I have to win.' 

If Shinra won, then he knew that he could return to the world of Naruto, and by then, he could start to develop his Mangekyou Sharingan ability, the Eye of Usurp and the Eye of Beyond, and also relax. 

As he thought so, he looked at his palm before he clenched his fist tightly, thinking that the time he had been waiting for was coming.