The obvious fight that happened was when Luffy came to Wano Country, where Kaidou resided.
Yes, at this moment, Luffy used Wano Country as his base, along with everyone. Naturally, he saw how evil the ruler of Kaidou was, and it was even worse as Orochi, the nominal leader of this country, further exacerbated the situation, forcing everyone to eat trash to survive, causing many to die from hunger or poison from the numerous factories created by Kaidou.
Yet, could Luffy stop everything?
The answer is yes.
The factories aside, Luffy had no need for Orochi, and with his charisma, it was easy for him to take control over this country as everyone would be under him, following him happily, yet while everything was easy, the remnants of the previous daimyo, or lord of Kouzuki Oden, and all others were unhappy with Kaidou.
Yes, Orochi might have been punished, but what about Kaidou?
Those people wanted to deal with Kaidou, and they were confident that they could win as they had Luffy's support, especially when, according to the prophecy, Luffy was the savior that everyone had been waiting for, but unfortunately...
"Stop fighting! You can all fight later, but now, be at peace!"
Luffy, no, it should be Nika, couldn't let Kaidou be defeated or die yet, as he needed Kaidou's power. He knew well how strong the World Government and Kaidou were, and because of that, he needed to gather as many people as possible to support him, but unfortunately, the hatred that Kaidou and the Wano Country had for each other was so deep!
How could those from the Wano Country tolerate Kaidou?
Yet at the same time, they were also angry at Luffy, whom they thought of as the savior, but why did he save Kaidou?
Was Luffy really the savior?
Would Luffy be like Kaidou in the future?
When they thought so, their feelings turned complex, and then they soon gathered together as they made up their minds to save this country by themselves!
"....." Nika.
Who was Nika?
He was the savior of this world, so how could he not notice the thoughts of those people?
Were they really so small-minded?
"You should just erase all of them."
Kaidou drank his alcohol lazily, as he had never thought of those remnants of the Wano Country as his opponent at all!
After all, how could he even take care of those useless people who could only rely on Luffy for revenge to do anything?
As for Luffy betraying him, Kaido knew that the chance was small, but even so, it didn't mean that he wasn't prepared. Then again, if he was forced to, then he might as well join the World Government since he knew that this world was as good as Shinra's.
Shinra Uchiha.
Instead of Nika, Kaidou felt like Shinra was the one, the one who tore away everything known as fate, destiny, and everything that was pre-determined, as Shinra made his own story, tearing everything away.
Yes, they might be an enemy, but Kaidou respected him since Shinra was the only man who could fight him head-to-head, toe-to-toe, like a man.
Or rather, even if Shinra faced so many opponents, whether it was Linlin, Newgate, and all others, he stood up again and again, never giving up.
On the other hand, what about Nika?
As Kaidou thought so, he sighed, yet this sigh was seen by Nika, which made him gloomy.
Yet, what could Nika do?
The revolution, the liberation, and to save this world from the World Government, Nika needed Kaidou's strength.
The power of the Wano Country aside, all of the pirates were together, this time, whether it was the remnants of the Whitebeard Pirates, the Big Mom Pirates, and all others, gathered together to fight the World Government!
Yes, on the Whitebeard Pirates, there was one member who hated Kaidou, but the others didn't hate Kaidou much, and they knew what was important for them.
Yet, the Wano Country was different, as it was isolated, and it didn't know how fearsome the enemy was that they faced. Instead, their enemies had always been Kaidou, the one that they hated the most, and they had never thought of the enemy outside, so before Kaidou decided to kill them, or Nika decided to betray them, they had to make a move, and fortunately, due to Nika, they knew what they should do.
As they walked toward the bottom area of their country, their eyes brightened as they saw a weapon that could protect everyone.
"By the way, you should watch the people of the Wano Country more," Kaidou suddenly said.
"What's wrong? Are you afraid that they might kill you or something, Kaidou?"
Everyone couldn't help but make fun of Kaidou, but he was at ease and said, "You underestimated their pettiness. As long as you make them doubt you slightly, they will still strike you down when you don't expect it."
"You don't have to worry! I will take care of everything!"
As Nika showed his trademark laugh, thinking that everything would be under control as usual, he thought that it was also a time to get the One Piece and the giants, as they were necessary, and staying in Wano Country too long also gave him a bad omen somehow. Then, as expected, his omen had been right, yet even so, he had never expected that the people of Wano Country would try to kill all of them by using the ancient weapon, Pluton.
By then, the explosion had destroyed the wall that protected the Wano Country, and everything fell, exposed, and no one could protect this country anymore, making the country even worse.
As for Nika and the others, the damage that they received after being hit by the Pluton directly was so great, and frankly, no one really knew where they were.
Did they hide?
Or, did they try to recover, then gather their strength to become stronger?
Yet, the truth was, Shinra was speechless since he won without him, didn't even need to do anything.
"Is this for real?"
Still, it didn't matter since as he controlled this world, along with the World Government, then soon, the water subdued and the land returned, and by his leadership, this world reached into a glory that no one could imagine before as they soon forgot about the Big Kingdom, or Nika, who they had always worshipped and wished to save them from their horrible lives.
After all, their current lives were comfortable, so why did they need Nika?
"Well, is it over?"
As he thought so, he overlooked the world of One Piece and thought that his journey was quite tough, yet it was all worth it.