The basic effect of Observation Haki was to sense the presence, emotions, movements, and so on of living creatures nearby, allowing one to evade attacks and detect hidden enemies.
This was actually a relatively advanced application of ki.
The Marines' training manual also recorded that when someone's Observation Haki reached a certain level, there was a chance they would awaken a unique form of Observation Haki with special effects.
Zhu Mang knew about that.
For example, Katakuri of the Big Mom Pirates, as well as Luffy after receiving "careful instruction" from Teacher Kata, possessed the ability to [See the Future]. They could use Observation Haki to glimpse scenes a few seconds ahead and respond accordingly.
The late Princess Otohime of Fish-Man Island, on the other hand, could use Observation Haki for [Emotion Sensing], allowing her to feel the various emotions within others' hearts.
Some people also possessed Observation Haki with an extremely vast range. Take the unlucky Enel, for instance. Through his own exploration, he had acquired top-tier Observation Haki capable of covering the entire Sky Island, only to be forcibly defeated by the protagonist.
Then there was the future Marine admiral Fujitora, who could sense meteors in outer space before using his Press-Press Fruit to drag them down in a meteor-fall attack.
There was also the [Voice of All Things], which could be used to communicate with creatures such as Sea Kings and Zunesha. Its users included the former Pirate King Roger, the protagonist Luffy, and the princess of Fish-Man Island.
In fact, Dragon Ball had similar methods of using ki.
Piccolo and Son Goku had both used ki to probe memories, communicate through long-range Telepathy, and so on.
The Grand Elder of Namek could even draw out the potential within others.
There was also Tien Shinhan's [Four Witches Technique], among other things.
These skills were clearly no longer crude methods of attacking and defending with ki, but higher-level, more subtle applications of it.
So if he wanted to draw parallels from the Haki of the One Piece world and learn how to use his own ki, starting with Armament Haki would be of little use. Advanced training in Observation Haki might be what benefited him the most!
Of course, there might also be the last of One Piece's Three-Color Haki.
It simply was not recorded in the Marines' Haki training manual.
Conqueror's Haki!
In the original story, this type of Haki was called the "qualities of a king," supposedly something that only one person in a million could possess.
Though judging by the later parts of the manga, you could not even make the cut without Conqueror's Haki, it was still ridiculously impressive.
And Conqueror's Haki actually had quite a few applications.
Ordinary Conqueror's Haki could be used to clear out fodder. After two years of training, Luffy could knock out a hundred thousand fish-man grunts in Fish-Man Island's plaza in one go.
More advanced uses included Conqueror's coating—like Teacher Kaido's Thunder Bagua—Conqueror's shockwaves—like Shanks remotely injuring the disgrace of the admirals, Ryokugyu—and producing an "internal destruction" effect when combined with Armament Haki, as in Luffy versus Kaido.
Furthermore, top-tier Conqueror's Haki could even affect changes in the weather.
If Armament Haki, Observation Haki, and the ki of Dragon Ball still shared some common ground that Zhu Mang could learn from—
Then Conqueror's Haki truly differed too greatly from the Dragon Ball system.
It was more like a kind of spiritual power.
Of course, if possible, Zhu Mang naturally wanted to learn it.
But Conqueror's Haki was a rather mystical thing.
You either had it or you did not. There seemed to be no way to develop it through training after birth.
"Eh? Doesn't Doflamingo have Conqueror's Haki?" Zhu Mang suddenly remembered.
He closed the two books and casually tossed them aside.
The principles behind these training methods were actually quite simple. He had already finished reading and memorized all of them, so the two "secret manuals" were no longer of much use to him.
Meanwhile, elsewhere.
After leaving Zhu Mang's room, Doflamingo returned to his own.
He carefully considered how he could tie Lord Gebinz to the Donquixote Family's chariot.
Beautiful women?
He had not really paid much attention to the beautiful women in his family before.
He had been single-mindedly focused on his career. That was exactly the kind of man he was.
But on second thought, there really were quite a few outstandingly beautiful women in his family.
And whether it was their background or strength, they were both fairly decent.
Violet was the former princess of Dressrosa, King Riku's youngest daughter. She possessed the Paramecia-type [Glint-Glint Fruit], which allowed her to see through objects and even glimpse what people were thinking. She also had some offensive capabilities.
But against anyone even slightly strong, it was merely something to add a little excitement. It had no real destructive power at all.
Right, she should also have a niece, born to King Riku's eldest daughter. Her name was... Rebecca?
She was still just a teenage girl, right? Apparently, she was quite pretty too. Should he send her along to Lord Gebinz as well?
Mm, given Lord Gebinz's standards, two definitely would not be enough.
He should include that idiotic maid at home who had eaten the [Weapon-Weapon Fruit], too, so she would not cause him trouble.
As for Monet and Sugar...
They were family he had acknowledged, so it would not be right to send them away like gifts.
Besides, Monet needed to monitor that idiot Gas Man as he continued producing the raw materials for Artificial Devil Fruits. That business was tied to Kaido of the Beasts.
Sugar's ability was crucial to his control over Dressrosa.
But if it was only those three...
Should he go to the Pleasure District and buy some professionally trained women from that woman Stussy?
If a few were not enough, he would buy a dozen, or even several dozen!
He would get a few from every race!
As long as Lord Gebinz would support the Donquixote Family, all of it would be worth it!
Right, Lord Gebinz also liked to eat. Should he go kidnap a few chefs somewhere...
Just as Doflamingo was frantically talking himself into it, someone suddenly knocked on his door.
"Who is it? I told you not to bother me!" Doflamingo assumed some clueless Marines had come to lecture him again, and replied impatiently.
"It's me," said a voice he recognized from outside the door.
"Ah! Lord Gebinz!" Doflamingo froze. Delight immediately appeared on his face, though he was also somewhat puzzled.
Hadn't he said that he did not want to be alone in a room with a man late at night?
Could it be...
His expression began to shift unpredictably.
Damn it, even if I want the family to rise, I don't want to do it this way! Aaaaah!
Doflamingo screamed inwardly, but his hands obediently opened the door. He even silently stepped aside to make way.
However, he made up his mind that if Lord Gebinz truly could not restrain himself, he would risk offending the Marines and capture beautiful female Marines for him rather than quietly endure it himself!
"Show me your Haki," Zhu Mang said decisively as he entered the room.
"What Haki?" Doflamingo was a little stunned.
Before you continue