Professor Layton and the Diabolical Box Cheats

Art Gallery
After beating the game, go to the Top Secret section of the Bonuses menu. You'll be able to access an art gallery depicting various scenes from the game.

Character Profiles List
After you've beaten the game, go to the Top Secret section of the Bonuses menu. Inside, you'll be able to access profiles for every character in the game.
Character Profiles List: Beat the game.

Layton's Challenges: The Sweetheart's House
Under the Bonus Menu, you'll find an option called Layton's Challenges. These challenges are comprised of espcially difficult puzzles. They can only be unlocked by fulfilling specific criteria in the main game. One of them is called the Sweetheart's House, which contains Puzzles 148, 149, and 150. In order to access it, you have to beat the game.

Layton's Challenges
Layton's challenges are the hardest puzzles in the game. They are found under the bonuses section. Each one has a different way of being unlocked.

The Animal lover's House: puzzles 145,146,147: get the hamster to lose weight. it takes 30 step in a row to get the hamster to lose all the extra weight. also makes the hamster point out hit coins.
The Musicians House: puzzles 139,140,141: fix the camera and then take pictures of any place where the camera icon appears(there are 9). then find the 3 differences in each picture.
The Sweetheart's House (148, 149, 150): Beat the game.
the Tea Master's house: puzzles 142,143,144: get all the tea ingrediants to find the different tea brews. then when any character has sweat drops over them(28) give them the tea the ask for.