One Piece: Pirate Warriors 4 has three game modes which you can select. If you choose Dramatic Log mode you will be able to unlock the characters by playing through the story missions. Check out our Best Characters - Tier List guide to find out which ones are the best in the game.
Not all of the characters in One Piece: Pirate Warriors 4 are unlocked naturally through game progression. Some characters require certain conditions to be met before they become unlocked such as defeating a certain amount of enemies, collecting a certain amount of different coins, clearing a specific episode on the Treasure Log mode or clearing different Treasure Log episodes. You can view the conditions for a specific locked character at the 'Character Select' and 'Character Unlock Conditions' on the 'Player Information' menu. If you pre-ordered One Piece: Pirate Warriors 4 you will have early unlocks for Niji, Ichiji,and Yonji, and if you purchase the Digital Deluxe Edition you will have an early unlock for Katakuri. There are also 9 DLC characters coming in a Season Pass for the game at a later date but at the time this article was published details of who there are has not been released.
Kaido
Katakuri
Monkey D. Luffy
Big Mom (Charlotte Linlin)
Shanks
Whitebeard
Carrot
Ace
Sanji
Reiju
Hancock
Cavendish
Zoro
Akainu
Crocodile
Fujitora
Lucci
Kuzan
Doflamingo
Franky
Robin
Kizaru
Blackbeard
Law
Nami
Kid
Marco
Mihawk
Sabo
Ichiji
Smoker
Yonji
Buggy
Ivankov
Chopper
Brook
Bartolomeo
Jinbe
Hawkins
Bege
Tashigi
Niji
Usopp
Check out our How to Level Up Characters guide to find out how you can strengthen you characters in One Piece: Pirate Warriors 4.