Unlockable: Girl of the Month
Change your DS date on any month with the 1st. Example: 05/01(year doesn't matter) and you should have a special girl of that month in the shop. NOTE: You can only buy them once.

Unlockable: Holiday Items
Bat Treats: Play on October 31st - 400 Coins
Birthday (Boy): Play on your Birthday - 5 Coins
Birthday (Girl): Play on your Birthday - 5 Coins
Elf Skirt: Play on December 25th - 300 Coins
Jack Hat: Play on October 31st - 4000 Coins
Jolly Suit: Play on December 25th - 300 Coins
Merry Cap: Play on December 25th - 10 Coins
Snowflake: Play on March 17th - 250 Coins
Succubus: Play on October 31st - 321 Coins
Valentine (Boy): Play on February 14th - 300 Coins
Valentine (Girl): Play on February 14th - 200 Coins
Vessel Top: Play on February 21st - 700 Coins

Hint: New Items
Change the system date to a different time or date to get new items in the shop. This works well for going back and getting items you missed or going forward to items you can't wait for (for example, Christmas).

Hint: 50 Coins Every Time
When you start just click credits and every time you watch the credits, you get 50 coins!

Hint: Don't Lose Your Money
If you lose money in hi-lo quickly press the mini-game button and click yes on “end mini game” and you won't lose your money. Note: Press this before they take your money.