Enchanted Arms prequel manga that came with the Limited Edition version of the game.
It's about a student named Kana who the player meets in London City after a certain event.

The Golden Age of Pirates

In 1715, pirates established a lawless republic in the Caribbean and ruled the land and seas. These outlaws paralyzed navies, halted international trade, and plundered vast fortunes. They threatened the power structures that ruled Europe, inspired the imaginations of millions, and left a legacy that still endures.

Into this world sails a young, cocky, and fearsome captain named Edward Kenway. His skill with a sword and disdain for authority earn him the respect of pirate legends like Blackbeard, but thrust him into an ancient conflict that threatens to destroy everything the pirates have built.