One Piece is one of the most popular shonen series out there, and it's because series creator Eiichiro Oda seemingly has an endless well of ideas that flow together effortlessly. But it hilariously turns out that Oda really doesn't plan every intricate detail.
Oda recently revealed some of the story bits he made up on the fly, and although they weren't planned in advance each of these elements made huge waves in the story regardless.
There are major examples of such last minute, but monumental decisions such as Oda's decision to turn Lucci of CP9 into a villain, Shanks appearing toward the end of the Battle at Marineford, Viv being a princess of Alabasta, Ace being Gol D. Roger's son, and Doflamingo and Corazon being related by blood.
Each of these last minute decisions carry major weight in the series, and some are still being felt as Oda thought that some of the Supernovas introduced as part of the Worst Generation along with Luffy and Zoro have made it so far into the New World. Oda suspected he'd focus more on other characters by this point as well.
One major element that should get fans' attention is the quick decision to focus more attention on Trafalgar D. Law. Oda originally thought Eustass Kidd would be more important, but recent events in the manga would suggest even more attention for Law is coming in the future.
This all goes to show that while Oda has a plan, he's not adverse to changing certain story beats or elements to deliver a more entertaining story in the end. It's why his is one of the richest worlds in all of manga and anime.
If you're interested in the series, One Piece is currently in the middle of the “Whole Cake Island” arc and can be found streaming on Crunchyroll and Funimation. Eiichiro Oda's One Piece first began serialization in Shueisha's Weekly Shonen Jump in 1997. It has since been collected into over 80 volumes, and has been a critical and commercial success worldwide with many of the volumes breaking printing records in Japan.
The manga has even set a Guinness World Record for the most copies published for the same comic book by a single author, and is the best selling manga series worldwide with over 430 million copies sold. Eiichiro Oda revealed some news about One Piece's future in a recent interview as well.
Stating that he was about 80 percent done with the manga at this point with the Wano arc, fans are worried that the series may be coming to an end sooner than they thought. But it wouldn't be wrong to infer that the ending will most likely still be years away given how much of the world there is to explore.