Levely, also referred to as Reverie, is the biggest political event in One Piece. It is a global council that assembles every four years with representatives of fifty different rulers of kingdoms affiliated with the World Government. This paramount occasion is held at the holy land, Mary Geoise, atop the Red Line, and that is where opinions about world affairs are shared and vital resolutions made to shape the political scene of the One Piece world.
The Levely arc follows immediately after the Whole Cake Island saga in One Piece and marks the most important point in the series storyline. It spans from chapter 903 to 908 in the manga and episodes 878-889 in the anime adaptation. This arc contains some dense political information and includes a significant number of revelations about the structure of power in the world, making it very important for understanding the world of One Piece.
One of the most prominent features of the Levely Arc is the number of really famous characters from all around the series. Some of the more notable attendees include Princess Vivi of Alabasta, King Riku of Dressrosa, and King Neptune of Fish-Man Island. These characters bring depth to political discussions and emphasize the real influence Luffy has had so far in his travels.
The Levely arc includes new, introduced, and expanded characters. For example, it introduces Stelly, an adopted brother of Sabo who turned into a King of the Goa Kingdom. His dealings with Monkey D. Garp, who apparently is sticking with the Fish-Man Island royal family, further complicate the bonds of the latter factions with the World Government.
Most discussed at this level is Monkey D. Luffy's action against the Big Mom Pirates, which has huge repercussions on the world stage. At one end, it underlines the growing influence of Luffy and the danger he is to the established world order, a motif running throughout the series.
What is more, the Levely arc includes much of the revelations connected with the World Government and Mary Geoise: insight into the inner workings of the World Government, hints at dark secrets hidden within the Holy Land. Very often, such information adds to the all-encompassing mystery of the world of One Piece and paves the way for future confrontations.
One of the most dramatic moments of the Levely arc is that of the Revolutionary Army led by Monkey D. Dragon. What they accomplish here does much to affect the balance of power across the One Piece world at large. It also shows what the other big players are doing, like Big Mom and Kaido clashing—two of the Four Emperors—to really drive home the global scale of events happening during this period.
For narrative structure, the Levely arc serves to bridge major arcs. It consists of very important world-building, setting the foundation for future plot developments. Of course, one needs to note that some fans criticized the pacing of this arc in the anime adaptation since there is a problem with the episode-to-manga chapter ratio and heavy usage of flashbacks. However, most of this is considered crucial information to the understanding of the One Piece story as a whole by many.
The name of this event has long been a matter of controversy among fans and translators. Where many used "Reverie" in their translations, Eiichiro Oda has offered an official romanization—"Levely". It indicates the depth that can even reach the One Piece lore and the never-ending debate within the fanbase.