One Piece is full of mysteries, including the titular treasure that Monkey D. Luffy and the Straw Hat Pirates have worked towards since the series' inception. However, there is a mystery even greater than the One Piece that has been teased for just as long — the secret behind the Will of D.
Source：https://www.cbr.com/every-one-piece-character-who-carries-the-will-of-d-explained/
