Detective outfit - Pause the game and press Left, Right, Left, Right, Left, Right to unlock the Detective outfit.

Personal island - Successfully complete all tasks, then go to Capital Island, and watch the credits. You will now have a special island named after your character.

Swordsman outfit - Pause the game and press Down, Up, Down, Up, Down, Up, Down, Up to unlock the Swordsman outfit.

Tattoo Vest - Pause the game and press C, Z, C, Z, B, A, B, A to unlock the Tattoo Vest.