Read this article to find the meaning of the initial D. in Luffy's name in One Piece and the mystery behind the Will of D.
What Does the “D” Stand for in One Piece? - One Piece
What does the D. stand for? (Theory) : r/OnePiece
What Does the “D” Stand for in One Piece? - One Piece
The Meaning Of D. In One Piece - One Piece