Half a year after fighting alongside Kiryu in the Millenium Tower, Goro Majima, amidst the debris of a shipwreck, washes up on an island beach. A young islander, Noah, saves his life, but Majima awakens with no memories—not even able to remember his own name. The only hints about his past are the tattoo on his back and the dagger by his side.

Suddenly, pirate-like ruffians who seem to have come from the Age of Discovery appear. After swiftly dealing with them and hijacking their ship, Majima decides to embark on a high-seas adventure to regain his memories and repay Noah by fulfilling his dream of seeing the world.

However, rumors of a legendary treasure have stirred up the waters around the outlaw paradise known as Madlantis. Captain Majima and his crew are about to take the plunge into the powder-keg world of seafaring scoundrels.