MySims Kingdom Detective outfit
Pause the game and press Left, Right, Left, Right, Left, Right to unlock the Detective outfit.
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.
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.
Music artist references
On the elves island, place the pointer over the animals. Some of them have names like Buni Jovi (Bon Jovi), Bruce Sproingsteen (Bruce Springsteen), Bunno (Bono), and Toad Nugent (Ted Nugent).
The image featured at the top of this post is ©The Legend of Heroes: Trails of Cold Steel III key art / Original