One Piece is both one of the most popular shonen anime of all time, and it ranks among the longest-running, too, having even more episodes than its shonen big three competitors Naruto and Bleach. Given its immense length, most audiences would feel intimidated to finally jump into the One Piece anime from the start. The One Piece episode count is truly vast and is still growing, after all.
Source：https://www.cbr.com/one-piece-how-long-watch-entire-anime-series/
