Post-War Arc

The Post-War Arc is the twenty-third story arc in the series, and the fifth and final in the Summit War Saga, as well as the final arc in the first half of the One Piece series, continuing on from the Marineford Arc. The world reels from the death of Whitebeard, causing pandemonium to spread across the world. Luffy's mind and body are in critical condition, having not only endured infiltrating and escaping from Impel Down and battling through the Marines and Shichibukai at Marineford, but having all of his work come to naught due to Ace's death. Boa Hancock leads Luffy's allies to take him to Amazon Lily where he may recover from his severe injuries. As the Marines cool down from their great battle, Sengoku learns that the World Government is taking disturbing courses of action. Luffy begins to come to terms with his brother Ace's death, which leads to a flashback of when he met Ace, and his friend Sabo, for the first time. After being consoled by Jinbe, Luffy remembers that he still has his crew and expresses his desire to see them again

Story Impact
- With the war against Whitebeard over, and the New Age beginning, the whole world begins to change.
- The balance of the Three Great Powers decline after Yonko Whitebeard's death and the resignations of both Jinbe and Blackbeard from their positions as Shichibukai.
- The status of Gekko Moriah is unknown, after being attacked by Doflamingo and the Pacifistas as an order by the World Government.
- Garp and Sengoku abdicate their positions, and Aokiji becomes a candidate for Sengoku's rank as Fleet Admiral.
- Smoker is transferred to G-5 in the New World.
- Crocodile, Daz Bones, the Blackbeard Pirates, and the Eleven Supernovas (except Luffy, Zoro, and Trafalgar Law) travel to the New World as well.
- Luffy's backstory about how he met and began his brotherhood with Ace is shown.
- Luffy and Ace's foster mother is revealed to be Curly Dadan.
- In the flashback, his second brother Sabo who is presumed deceased is shown.
- In the flashback, Sabo's parents adopt another boy in the case Sabo would fail named Stelly who, as revealed in the Whole Cake Island Arc is now the King of the Goa Kingdom.
- The S crossed out on Ace's arm is not an error but a homage to Sabo.
- During this flashback, Bartholomew Kuma is seen with Dragon and Ivankov as a revolutionary.
- Sabo's talk with Dragon would foreshadow his return in the Dressrosa Arc and his involvement with the Revolutionary Army.
- After having a talk with Jinbe, Luffy decides to reunite with his crew but regroups with Rayleigh who develops a plan to regroup with the other Straw Hat Pirates by sending a message via Luffy's tattoo, 3D2Y meaning not to meet back at Sabaody Archipelago in 3 days as they planned, but in 2 years so they can train.
- Chopper studies advanced medicine in Torino Kingdom.
- Sanji begins to learn the ninety-nine Attack Cuisine recipes in Kamabakka Kingdom as well as fighting 99 Newkama Kenpo masters.
- Nami begins to learn about the New World's meteorology on Weatheria.
- Brook composes a new song for the Longarm Tribe on Kenzan Island.
- Robin goes to Baltigo to join Dragon and the Revolutionary Army.
- Franky begins to study Dr. Vegapunk's explorations into weaponry on Karakuri Island.
- Usopp begins survival training from Heracles in order to eventually escape from the Boin Archipelago.
- Zoro begins to train under Mihawk on Kuraigana Island.
- Luffy begins to train with Rayleigh who begins teaching Luffy how to use Haki on Rusukaina.
- Brownbeard's defeat at the hand of Basil Hawkins' would cause him to lose the usage of his legs and find his way to Punk Hazard and become an alligator centaur and a subordinate of Caesar Clown.
- In Luffy's training, it is finally revealed that there are three different forms of Haki.
- Kenbunshoku Haki (known as Mantra on Skypiea) which allows the user to predict their enemy's movements.
- Busoshoku Haki, the ability which allows people to create a force which allows their attacks to become stronger, and even attack other Devil Fruit users without problems, especially Logia's.
- Haoshoku Haki, the ability which one in a million people have and grants the ability to intimidate their enemies.
- The foreshadowing of Smoker's role in the Punk Hazard Arc, Trafalgar Law becoming a Shichibukai, and Aokiji battling Akainu for the title of Fleet Admiral are all shown in some form.
- The letter sent to Buggy would foreshadow him becoming a Shichibukai after the timeskip.