Every character who knows the location of the ancient weapons

Ancient weapons are one of the most important plot points a piece. As the name suggests, these weapons were created in ancient times, and they carry great destructive power. In fact, it is said that ancient weapons have the power to destroy the entire world if they fall into the wrong hands.

Such weapons of mass destruction were essentially built by none other than the people of the Ancient Kingdom, who possessed incredible scientific prowess. While the ancient weapons were used on a fragmented world long ago and were responsible for sinking it 200 meters under the sea, they are still active, waiting to be used, and only a few people know their location.

8

The Royal Family of Fishman Island

The royal family of Fishman Island consists of King Neptune, his three sons and a daughter. Neptune's own daughter, Shirahoshi, is an ancient weapon, also known as Poseidon, the Mermaid Princess. Naturally, the family knows about Shirahoshi's true nature and that he will one day help reshape Fish-Man Island after the Joy Boy regenerates.

They are all waiting for his powers to awaken, and that successfully happened in the Fishman Island arc, especially towards the end, when Shirahoshi was able to command the Sea Kings to stop Noah from destroying the entire island.

7

Caribou

The caribou's main role in the story was to get key information to a specific person who would be touched later. Caribou was in the Fishman Island Ark, and although he didn't actually play much of a role, he successfully overheard a conversation between the Straw Hat Pirates and King Neptune. From this he found out that the Shirahoshi was an ancient weapon and had enough power to destroy the entire world.

Caribou were seen again in Wano. There, he once again overheard the conversation surrounding ancient weapons. This time, he discovers that Pluto's location is under Wano country and he needs to open Wano's border to open the weapon.

6

Blackbeard (via Caribou)

Image via Toei Animation.

Blackbeard did not know the location of any of the ancient weapons until now. However, Caribou recently met the Blackbird Pirates and had key information to give them. In fact, it was revealed to the fans that Caribou was actually a big fan of Blackbird and was the main reason he traveled in the first place.

Now, Caribou is going to sell all the secrets to Blackbeard and reveals to him the location of both Pluto and Poseidon. This information will have a big impact that we can't wait to see in the second half of the final saga of One Piece. It is also very likely that, along with Blackbeard, his pirate crew is also privy to this key information about ancient weapons. What they do with this information further remains to be seen. It is entirely possible that they will attack the Wano country or, at least, attack Fishman Island. Either way puts them in direct conflict with the Straw Hat Pirates, which is something we as fans can't wait for.

5

Straw Hat Pirates

Straw Hat pirates don't care about ancient weapons. However, that doesn't mean they don't know about any weapons. In the Wano Country arc, Nico Robin clearly informs the Straw Hat Pirates that Pluto is actually sleeping under the Wano. Robin asks Luffy if he wants a weapon, to which he replies that he doesn't care.

Still, Luffy and the other members of the Straw Hat Pirates now clearly know where the ancient weapon Pluton is. This is very interesting and is definitely going to play out later down the line. At some point, Luffy is forced to use ancient weapons, and this is also foreshadowed through the Fishman Island arc, which officially states that he is going to destroy the island once and for all. Considering that only weapons like the Ancient Weapons have the abilities to pull things like this off, it's highly likely that Luffy will use them sooner or later.

4

Nico Robin (Poseidon)

Nico Robin is a part of the Straw Hat Pirates and thus should be included in the previous entry. He has knowledge of more than one ancient weapon that other members of the crew do not. Nico Robin also knows about Poseidon's location on top of Pluto. She only divulges Pluto's location to the crew, while Poseidon's knowledge is still with her.

Nico Robin found this information in the Fishman Island arc, and there, it was clear to fans that he read the poneglyph in the Sea Forest and discovered the truth about the weapon. She also knows about Joy Boy and his return, and it will be interesting to see what this knowledge is going to do for Robin later.

3

Emus and Elders

Apparently, Emu and the Five Elders are aware of the ancient weapons and their locations. Fans know that the Elders wanted to see Wano's borders open specifically because of the location of the ancient weapon Pluto. More importantly, they also have ancient weapons at their own disposal. The ancient weapon Uranus was recently revealed to be in Emu's possession, and the Elders used its power to destroy Lulucia, after the Mother Flame was stolen from Vegapunk.

Now that Vegapunk Lilith has officially sided with the World Government and is officially producing more Mother Flame, it's only a matter of time before the old weapon Uranus is charged up and ready to go again. With more Mother Flame, this weapon will become a nightmare for those who stand against the World Government, as it can submerge islands and, with it, the world of One Piece further on.

2

Kozuki Sukiyaki (and Momo and Hiyori, potentially)

Kozuki Tsukiaki is another powerful figure known by fans to hold the secrets of the ancient weapon. As Daimyo of Wano, he knows the location of the Pluton, and tells Robin that the weapon is in Wano's land. He may have also sent this information to Momo and Hiyori, especially now that the former was the Shogun.

1

Trafalgar Law

When Kozuki Sukiyaki revealed the location of the Ancient Weapons Platoon, Trafalgar Law was also present on the scene. As such, he also knows the location of this ancient weapon. His interest, he said, is more in the history of the D than why these weapons exist and what their purpose is. Still, this piece of information might come in handy for him later in a piece down the line.

All the latest chapters of Eiichiro Oda's One Piece manga are available to read through Manga Plus and Viz Media.