One of the biggest advantages of long-format storytelling is being able to introduce tons of information while also setting up plot threads and lore way in advance. Few mangaka are better at this than Eiichiro Oda, creator of One Piece.
Oda excels when it comes to foreshadowing, willing to leave small breadcrumbs in one chapter and then reward the most patient of readers hundreds of chapters later. Ahead of the 1,000th chapter release of the series, let's examine some of Oda's best uses of foreshadowing.
Haki
Some may say Haki is something Oda came up with later, but signs of its existence have been around from the very beginning. After Shanks loses his arm to The Lord of the Coast while trying to save a young Luffy, the pirate gives a terrifying death glare to the Sea King, telling it to "Get Lost." Fans point to this moment as the first sign of Haki, with Shank's using his Conqueror's Haki to terrify the serpent and make it lose its will to fight.
Much later on, Haki is seen again, but in a different way and under a different name. The Skypiea arc had the Straw Hats face off against Eneru and his four priests, all of whom have an ability known as Mantra, which allows them to sense an opponent's position and attacks before they happen. Clearly, this is Observational Haki under a different name. It wouldn't be until the time skip that it would be used more frequently by the Straw Hats.
Silvers Rayleigh
This is perhaps Oda's most rewarding planted payoff. During the Buggy arc, a flashback reveals Buggy the Clown and Red-Haired Shanks served on the same crew as kids. It shows a man scolding Buggy and Shanks for arguing like little boys often do. 500 chapters later, readers learn this man is Silvers Rayleigh, one of the most infamous pirates to have ever lived and the first mate to the King of the Pirates himself, Gol D. Roger. What's even more shocking about this is the fact that both Shanks and Buggy were cabin boys on the Pirate King's crew.
Sanji's Past
Sanji has been a contentious Straw Hat among fans -- he has a cool demeanor, but also a difficult-to-get-past "girl crazy" personality. There was always seemed to be a bit of mystery behind the ship's cook. This began during the Jaya arc when Sanji revealed that he only grew up in the East Blue, but he was actually born in the North Blue. An odd detail, but this wouldn't be the last we'd hear of it. Later in Thriller Bark, when Zoro is offering himself in exchange instead of Luffy to Bartholemew Kuma, Sanji steps in, saying he'd be "worth more than both of them." Fans also speculated this may refer to his past as well. This cumulated after Dressrosa when Sanji's new bounty poster stated "ONLY ALIVE."
Following into the Zou arc, we finally get the answers to Sanji's past, as it's revealed his surname is Vinsmoke and he's actually the 3rd son of the infamous Germa Kingdom Royal Family. The fact that Oda waited so long to give answers on Sanji's missing past made it so much rewarding when we finally got there. He left so many clues and breadcrumbs about it, offering a lot of room for fans to theorize for years.
Laboon and Brook
When Luffy and his friends first cross Reverse Mountain into the Grand Line, the first thing they're greeted to is a whale so massive they mistake it for a mountain. They learn from Crocus, the overseer of the twin capes lighthouse, that the whale's name is Laboon and he's been waiting for 50 years for the pirate crew he befriended to return from their adventure across the Grand Line. A sad tale without question, but Luffy manages to befriend Laboon, promising that he'll one day return to visit him when their adventure is over. It seems like a little one-off story, but it ends up paying off later on.
When the Thriller Bark arc rolls around, readers meet Brook, a musician skeleton trying to get back his shadow. They then learn that Brook is so desperate to get back his shadow so that he may keep a promise he made to a friend a very long time ago, that friend being Laboon. After Luffy tells Brook he met the whale and he's doing well, the well of emotion that consumes Brook is immense, and the skeleton cries repeatedly. Now knowing that the small whale has grown up and is still waiting for him, Brook agrees to join the Straw Hats as their musician, with the hope of returning to Reverse Mountain at the end of their journey and reunite with Laboon.
Will of D.
This is perhaps One Piece's biggest unsolved mystery of all. It starts with Monkey D. Luffy, as for the longest time, Luffy was the only character who had a middle initial. Nobody was sure what it meant until the end of the Drum Island arc when Dr. Kureha refers to Gold Roger as Gol D. Roger. This comes as a big revelation, as she says "The Will of D. lives on…"
As One Piece progresses, more individuals sharing this "D." initial are introduced, like Portgaz D. Ace and Marshall D. Teach. The Will of D brings supposed chaos by those who carry it. In Dressrosa, Corazon reveals that those who carry "D." are the natural enemies of the Celestial Dragons. It's worth noting that every person with the Will of D who has died has done so with a smile. There's still so much mystery to uncover in One Piece, and the Will of D. is undoubtedly one of the biggest.