In this theory I am going to talk about Joy Boy and the Ancient Weapons. Don’t get me wrong I am not talking about Joy Boy and the Ancient Weapon who exist during the Void Century I am talking about the new Joy Boy and the new Ancient Weapons who are part of the current era of the OPverse.
But before going to the new era I have to talk about the void century giving a brief summary of what we know to show what we can already conclude and what kind of hints it gives us about the new era.
Informations about the Void Century
800 years ago was the end(or beginning I am not sure) of a century which is now known as the void century, its called Void Century cause the World Goverment tried to erase all informations about this century and also prevent people from talking about it. But there exist the indestructable Poneglyphs written in a language with only a few left who are able to read, more precious the only known living character able to read this language is actually Nico Robin.
Nico Robin is from an island called Ohara known for the Scholars of Ohara a group of people who studied the history of the OPverse incl. to find out everything about the Void Century by decyphering the Poneglyphs. Everyone of the Scholars of Ohara (besides Robin) were killed by a Buster Call while Robin was still a kid. In Robins backflash Oda revealed the final words of Prof. Clover ther leader of the Sholar of Ohara.
These final words revealed a lot. During the Void Century there was an enormous Kingdom which prided itself for its great power. But this Kingdom doesn’t exist anymore it can be concluded that this Kingdom was defeated by an alliance of the 20 nations which have become the leading nations of the current World Goverment.
The next piece of important information is what we learned about the Poneglyphs on Zou. There it was told the Poneglyphs were created by the Kozuki Clan of Wano.
In the flashback of Oden we learned that the Kozuki Clan was also responsible for closing boarders of Wano that the clan did it to protect Wano from a great evil.
In my opinion its quite obvious that this great evil was the alliance which is now know as the World Goverment. With this one can conclude that the Ancient Kingdom ordered the Poneglyphs the moment they realize they are going to loose the war and that the Poneglyphs containing the informations about the Void Century were given to their allies. Meaning every nation who was in the possesion of a Poneglyph was an ally of the Ancient Kingdom. Besides history these Poneglyphs also contains thel locations and informations of the so called Ancient Weapons known Poseidon, Pluton and Uranus each of them capable of mass destruction.
These weapons are not only meant to be objects, but also living beings. Pluton is a ship while Poseidon is a Mermaid Princess able to control the Sea Kings while Uranus is still completly unknown. Combining that the Poneglyphs contains informations about the Ancient Weapons with the assumption that the Poneglyphs were ordered by the Ancient Kingdom and hand over to their allies one can conclude that the Ancient Kingdom and their allies were in the possesion of these Weapons. Another thing we learned about the Poneglyphs that there are 4 special Poneglyphs, known as the Road Poneglyphs. These Poneglyphs contain the informations how to reach the island Laugh Tale. This lead to the assumption that the Ancient Kingodom was domiciled on that Island.
Roger and his crew manage to reach Laugh Tale and learned anything about the past and a man known as Joy Boy. They also learned that Joy Boy will return 20 years later, which is “now” in the current One Piece timeline. Thats also why Oden decided to go back home and open the boarders of Wano.
This leads to the assumption that Joy Boy was something like the leader of the Ancient Kingdom. And since we learned that with Joy Boy also Poseidon have to return at given time
I am going to say that also the other 2 Ancient Weapons will return too.
