By having save data from the previous three Picross e titles on your 3DS, you can unlock five special puzzles. They appear as a gift icon next to the "Mega Picross" option.
Unlockable: --- How to Unlock:
S001-S005 --- Have save data for Picross e
S006-S010 --- Have save data for Picross e2
S011-S015 --- Have save data for Picross e3
When you are on the main menu display, you can get a gold medal alongside each mode's button. To obtain the medal, you need to complete each puzzle because mode in under an hour (each option have to be shown in color at the end).