One Piece is a mainstream manga by Eiichiro Oda and it's the best manga ever written! So if you don't know it yet, go read (or watch) it and then come back!
The original story talks about Luffy D. Monkey, who is on his way to become the Pirate King, and his pirate crew. The manga has also beed adapted to anime and both are still ongoing.
The doujinshi work talks about Luffy x Zoro x Sanji and it's really adorable and hot!! It's definitely worth taking the time, to check it out guys!! <3
You can download it here~