Four Emperors



The Yonkou (四皇, Yonkō), literally Four Emperors, are the 4 great pirates who rule the second half of the Grand Line (known as 'the New World').

They are one of the 3 great powers, the other being the Shichibukai and Marines and live quite literally as though they are Emperors, doing mostly as they please. For the World Government, these are the greatest pirate threats in the world. It is only through the combined efforts of the World Government and the Shichibukai that keeps their power in check. Each of them is equal in strength to Whitebeard and whenever there is a shift in the balance of the 3 powers one of the 4 Pirate Emperors makes a move.

The 4 Emperors themselves are not united together as one group like the Shichibukai and live by their own individual paths in life. For that reason, the World Government does not want a meeting between Red-Haired Shanks and Whitebeard, fearing the 2 Emperors may unite together creating a stronger threat.

History
Much of the history of the Yonkou is unknown.

The first of the Yonkou to be introduced was Shanks who visited Luffy's hometown ten years ago, though it was unknown that the Yonkou existed at this point of time. The second was Whitebeard, the only man to tie in a fight with Roger and was later announced the strongest pirate in the world upon his death. Some of the Shichibukai were rivals to the Yonkou in the past; Shanks was a rival to Mihawk and Kaidou to Gecko Moria.

Shanks and Whitebeard are both famliar to the old days of piracey, before Roger's death 22 years ago, though it is currently unknown if the other two Yonkou are from the old days of piracey.

One of the more familiar movements of the Yonkou's history were to aquire strong fleets, including ship and elite crewmen. All Yonkou traveled to the New World at some point in their past, where they are currently locked in stalemate, unable to progress any further into the Grand Line. This is a product of the combined efforts of both the Marines and Shichibukai, as well as the presence of each other Yonkou in the Grand Line.

Until recently, the World Government has been fine with the world powers remaining as they are, with the Yonkou stuck in a deadlock situation as this allowed the world to remain stable. With the absence of Crocodile, defeated at the hands of the Straw Hat Pirates, they were alarmed with two of the Yonkou, Shanks and Whitebeard, arranged to met each other. Later with Enies Lobby in ruins, the Marines saw another defeat in the New World when a blockcade failed to prevent the two meeting.

Fearing the two crews forming an alliance, the World Government has resulted in laying in wait to see what happens. Shanks believes the days of Whitebeard as the top pirate are coming to end, warning him of the era to come. With Blackbeard now making his move to the top, the pair are last seen clashing weapons.

List of Pirate Emperors

 * 1) Shanks
 * 2) Whitebeard
 * 3) Kaidou