One Piece stands as one of the longest and best shonen anime series of all time, but it's not just one giant story arc. This franchise is almost like an anthology, taking Luffy's Straw Hat crew on various unique but loosely connected adventures all over their fictional world. This means One Piece's journey is divided into sagas, each of which is broken up into shorter story arcs.
Source：https://www.cbr.com/best-one-piece-anime-arcs/
