Ero Ero No Mi – The Great Adventure

A young boy suddenly discovers an akuma-no-mi inside an old box, but unlike most, it doesn’t have any powers as yet. He keeps it and lives a normal life with his mom until that peace is ruined. Pirates kidnap his mom, and she never returns, so he becomes a sailor and vows he will somehow find his mom and their peaceful life can be restored. But it turns out the sailors are also unjust and he ends up becoming a pirate.