There is a great item, perhaps the best one in the game, hidden on the first floor of the labyrinth. It is the Happiness Ring, which gives you 10x experience and Gold for defeating monsters. Here is how to find it:
Step 1: Access the camp menu, and select "Options" > "Access Config" option (Options can usually be found on the second page)
Step 2: Select "No." This increments a hidden counter. Note: This counter is saved to your game file, so if you go over the proper number, you can never go back!
Step 3: Do the "Access Config" option and select "No" three more times for a total of four. You will know you are on the right track if a new menu item "Key Config" appears on your third attempt. When this happens, you only need to do "Access Config" > "No" one more time.
Step 4: Go to the first floor of the labyrinth and move to the square marked below. Face left (this is mandatory!) and press enter.
If the ring still doesn't show, walk into the wall just enough to change Custom's current frame of animation. This is a game-wide problem with objects on walls that is fixed by this patch, but can also be circumvented by walking into the wall as described above.
The ring will definitely save on some level grinding! ;-)
If you play Toushin Toshi 3.9 Ver.5.32, you can rename the protagonist's name by pressing Esc with the right timing on the Title Screen (wait until the opening text scroll begins and hit Esc). A window for renaming will be opened and after pressing ok and beginning a new game, the name of the Protagonist will change.
There are three girls trapped in mirror fragments in this. Of the three, one is required to get from chests on floor 8, but the other two are random drops from enemies on specific floors that give rewards when found. Each girl counts as two cgs. Girl 1's fragments are found on floors 1, 2, and 3 and gives 2,000 experience when found. Girl 2's fragments are found on floors 5,6, and 7 and gives 3,000 experience when found.