Episode 314

"The Strongest Family Lineage? Luffy's Father Revealed!" is the 314th episode of One Piece.

Long Summary
Luffy's Grandfather has been revealed to be Monkey D. Garp, Marine Vice-Admiral and celebrated hero. Garp expresses disappointment that his torturous training regimes did not inspire Luffy to follow in his footsteps and become a Marine. The two continue to argue and Garp reveals that Shanks, the man who inspired Luffy to become a pirate, is a member of the Yonkou. Four powerful pirate captains who rule over a part of the Grand Line like emperors and who are the reason for the creation of the Marine Headquarters/Shichibukai alliance.

Garp's speech is cut short by Zoro, who arrives back at the Galley-La Company compound and begins fighting the assembled marines. Unfazed, Garp instructs his two best students to combat Zoro. However the two are easily subdued by Luffy and Zoro and revealed to be faces from the past, Luffy's former companion Coby and his former enemy Helmeppo. Luffy warmly greets his old friend, while snubbing the irate Helmeppo, much to his annoyance. Coby explains that both he and Helmeppo have been training under Garp in order to become Marine Officers.

Garp continues his speech, revealing that Luffy's father is none other than the infamous revolutionary Monkey D. Dragon, who had been responsible for saving Luffy's life back in Lougetown. Robin explains that Dragon is head of a force that directly opposes the World Government, the Revolutionary Army. As this force has already been responsible for the overthrow of several monarchies, the World Government have labeled Dragon the most dangerous criminal in the world.

Garp concedes that he has probably revealed too much and instructs everyone to forget what he said.