The answer to that question is pretty obvious—
The "Heavenly Tribute" is essentially a yearly tribute paid by the 170 nations affiliated with the World Government to the Celestial Dragons. In theory, it's not just money, but also local specialties from each country. Once collected, all of it is handed over to the Marines, who then escort it to Mariejois, the Celestial Dragons' holy land.
In the original story, there were a few brief scenes about the "Heavenly Tribute," but they were so short that most of the group members who had seen some of the series, like Uchiha Hikari, Bulma, and Eriyi, didn't recognize it. Only those who had read the whole manga knew about it.
So... why would Bulma suddenly bring this up?
Could it be that... she ran into some high-ranking officials from an affiliated nation who were squeezing the common people for money?
[Bulma: That's exactly it.]
[Bulma: Over the past few days, Akame, Leone, Tanjiro, and I have traveled quite a bit around the Kingdom of Sara—the island nation we're staying on now. We heard some things from the locals. While not everything is confirmed, from what we know, the actions of these government officials are no different from the corrupt officials back in the Empire. They're taking away the people's food just to give it to the nobles. I don't think that's right.]
[Nameless: So... are you thinking about starting another revolution here?]
Uchiha Hikari's eyes flashed. She knew the general situation in the world of One Piece. Beneath the surface of freedom and adventure, this world had a very dark side.
From the four seas to the Grand Line, from Orange Town to Wano, most of the people in this world live a life of hardship and oppression. This oppression comes from pirates, the Marines, and the Celestial Dragons.
Powerful individuals like Whitebeard and Kaido are the exceptions. People like Luffy and Ace, who have special backgrounds, lots of connections from birth, and the good fortune to eat a useful Devil Fruit, are also rare.
The vast majority of ordinary people are robbed, exploited, forced into slavery, or made to work in miserable conditions. They eat and drink contaminated food and water, and are even used as test subjects for human experiments. Wano had a secret base for such experiments, overseen by Queen the Plague, one of the Three Disasters.
It's a ridiculous, but cold, fact: under the rule of the Four Emperor Big Mom, Whole Cake Island, which extracts years of life in exchange for a place to live, is one of the most livable places for ordinary people in the One Piece world.
As a transmigrator, Uchiha Hikari could detach herself and look at these things from a higher perspective. But for Bulma and Leone, who came from humble backgrounds and experienced similar injustices that led them to join the revolution, it was difficult to ignore.
However... since the One Piece world is Yamato's main stage and Ace's situation is more urgent, Bulma was a bit reserved in her words:
[Bulma: It's not really a revolution. I just want to do something for these people, even if it's just taking out a few corrupt officials and giving them a temporary break from the Heavenly Tribute. Miss Bulma, would you allow Akame, Leone, and me to take a few days off? That is, if there's nothing urgent happening with the pirate crew.]
[Bulma: Hmm... taking time off is totally fine.]
[Bulma: But... Bulma, are you really not going to start another revolution here, like Hikari suggested?]
[Bulma: ...Huh? Are you serious?]
[Bulma: Cough, cough... While it might sound bad, I was really curious about what you guys did back in the Akame ga Kill! world. I'm a little sad I couldn't be there. How about you bring me along this time and we all cause some major chaos here?]
[Bulma: Of course, we still need to prioritize Yamato and Whitebeard's situation first.]
Bulma wasn't kidding. She loved to stir things up. Choosing to experience the pirate life in this world already put her at odds with the World Government. If she could cause a big scene in the One Piece world, Bulma was more than willing to do it.
But... Bulma was a bit lost. While he had debated politics in the chat a few times, he hadn't thought that far ahead.
[Bulma: This... a "revolution" isn't that simple. It requires support from the people. We're just a few outsiders from another world; I don't think we could...]
[Bulma: It's fine! We can team up with the local Revolutionary Army. I think there are a few of their cadres in Impel Down, right? Or, we could find Luffy's father, who is the leader of the Revolutionary Army. That should lead us to them!]
[Nameless: ...By the way, Bulma, did you find out when the Sara Kingdom is paying the Heavenly Tribute?]
[Bulma: I think it's sometime soon, but I'm not sure of the exact date.]
[Nameless: If that's the case... then let's go big. The "Heavenly Tribute" isn't just oppressing one country, it's oppressing all 170 affiliated nations. Rescuing the Sara Kingdom alone would only be a temporary solution. How about we steal all of the Heavenly Tribute from all 170 countries at once?]
There was a precedent for this. Donquixote Doflamingo had done something similar once, using the Heavenly Tribute as a bargaining chip to become a Warlord of the Sea.
But for Uchiha Hikari and her friends, the title of "Warlord of the Sea" was worthless. They just wanted to have some fun and turn the whole sea upside down.
---
In just a few words, the plan to "hijack the Heavenly Tribute" was temporarily decided. It was definitely going to happen, but the specific action plan still needed to be discussed. After all, they didn't even have the basic information, like the tribute schedule or the Marines' escort route.
After a brief discussion, Bulma and Akame took on the responsibility of gathering intelligence. Uchiha Hikari, after finishing her tasks, traveled back to the One Piece world. There, she, Esdeath, and the rest of the Whitebeard Pirates welcomed a long-awaited guest: half a month after Rockstar failed to deliver his message to Whitebeard, Red-Haired Shanks's crew appeared in their waters.