Hydreigon, Wano Kuni form, due to its origin from the Yamata no Orochi Fruit, originally evolved from three heads to eight, but this doesn't have much impact.
Originally, the Hydreigon has three heads, but only the middle head is the real head, while the heads on its arms are brainless.
Additionally, Hydreigon does not have any legs, and the blue, elongated objects on either side of its tail are not its legs but rather underdeveloped tails like the ones on its arms.
This is why Hydreigon typically does not land on the ground, choosing to hover at low altitudes instead.
Now with its transformation into an eight-headed dragon, the brainless heads have also increased to seven, and there are seven smaller tails beside the thick tail, visually resembling Yamata no Orochi.
Even the color has inherited the primarily green hue of the Yamata no Orochi Fruit, perfectly matching Hydreigon's alternate color form.
However, those seven heads are still brainless, controlled by the will of the middle head. They can perform normal actions like roaring and eating.
At this time, the eight-headed dragon is hovering over Ghost Island, and its special wings contain peculiar Dragon Type energy, allowing it to maintain this flight. Unlike Tyranitar and Emboar earlier, the dragon radiates a fearsome aura.
Some laborers from Wano Kuni below Ghost Island saw the newly emerged giant beast, a symbol of fear once again appeared, resembling Yamata no Orochi, a creature known in legends to bring disaster.
But this fear quickly transformed, as the creature did not cause destruction but instead showed submission, even a destructive creature chose to submit, which caused many people's mindsets to change further.
Especially when they discovered that, not long after, the Guardian King of Wano Kuni was riding on the back of that monster.
...
"Hohoho, this guy is pretty good, it'd be better to have it follow me from now on."
He liked the ferocious aura, and was interested in the battle spirit of the eight-headed dragon, and such a flying, fierce giant beast matched his persona well.
Seemingly carefree, Kaidou actually pays great attention to the grand entrance. When appearing before newcomers, he chooses an extremely intimidating way, such as jumping from Sky Island, creating a large crater upon his landing.
However, during such a high descent, a bit of wind could cause a position shift. To land precisely in front of certain people, he had to adjust his position mid-air using his ability.
A suitable mount greatly enhances his grand entrance, and the persona of the eight-headed dragon satisfies Kaidou's needs.
Although it is of Yamata no Orochi's origin, it is a Pokemon remodeled based on Hydreigon; after all, it is a Dragon breed. In myth and legend, dragons hold the pinnacle position, be it righteous Dragons or villainous Dragons.
"Do as you see fit, but wanting it as a mount isn't something you achieve with a few words."
Arceus's primary purpose is experimentation, and for now, it seems that vivifying Zoan-type fruits is not difficult and the results are excellent. Arceus has no objections to the new role Kaidou plans for it.
"I know, I just like its kind of nature."
At this moment, the eight-headed dragon was staring intently at Kaidou, as if ready to pounce at any moment.
This is its innate nature, extremely fierce.
In the Pokemon World, Hydreigon is recorded as an extremely ferocious and terrifying Pokemon; trainers who can tame it are very rare, as Hydreigon sees everything as an attack target.
It did not choose to attack now only because Arceus was still in front of it. Though filled with destructive thoughts, Hydreigon-type Pokemon are highly intelligent and can recognize their true owner.
This aspect is also very much like Kaidou, high in intelligence but often too lazy to use it, in some sense, their compatibility is indeed not low.
Moreover, this eight-headed dragon itself is not as cruel as Hydreigon, only more combative and more solitary compared to other Pokemon.
In the Pokemon world, Hydreigon's species characteristics develop gradually; due to their fierce appearance, Hydreigon was always seen as an embodiment of evil, continuously despised and attacked by people, thus their nature became fierce.
Before evolving, the original form Deino has no vision; it can't see anything, experiences everything through biting, which easily injures other things in the process.
For Deino, things in the world are just categorized as edible or inedible.
This leads other Pokemon to dislike them, ultimately resulting in this situation.
"I really fancy you, from now on you'll serve as my mount."
Fearing no sharp teeth, Kaidou directly reached out to grab it, and the eight-headed dragon also promptly bit down.
"Pretty decent strength, you're indeed a good mount."
Feeling the force on his skin, Kaidou's smile widened.
"You've heard what your creator said, if you have any dissatisfaction, express it now."
"Roar!"
It had heard Arceus's words and understood that Arceus meant that this man could be its master, but it showed no direct sign of submission.
Apart from Arceus, it's not easy for others to tame it.
Although Kaidou didn't understand its language, he could feel the eight-headed dragon's intention.
Thus, the most primitive Pokemon taming action occurred here. It's hard to tame the eight-headed dragon with mere emotion; without sufficient strength, it's impossible, yet Kaidou just matched this disposition, engaging in a fierce hand-to-hand combat with the eight-headed dragon.
In the skies above Ghost Island, a drama of Kaidou against the deadly dragon unfolded. The eight heads of the dragon spewed attacks of different attributes: sharp rock spikes, scorching flames, roaring thunder all striking Kaidou's body.
However, this only heightened Kaidou's interest in it.
To demonstrate the master's capability, Kaidou, like a rock, took on all its bites and breaths using his body.
Finally, controlling the eight-headed dragon in a chokehold, he used his own strength to have it acknowledge him as its master.
Those fortunate enough to witness the confrontation between Kaidou and the eight-headed dragon from afar in Wano Kuni, returned home to recount their experiences, which ultimately led to a new play in Wano Kuni.
They adapted the narrative of the King of Protectors based on Kaidou and Yamata no Orochi's personas.