This menu requires a button code to access! Simply hold L1 and R1 when selecting the options menu from the title screen, and the "omake" option will show up on it (You'll know it's there, even if you can't read Japanese, cuz it'll be the only yellow-coloured option selection there). Entering it brings you to a nifty little cutscene viewer, which is cool, but that's not all! Pressing right on the D-pad will move your selection off of the cutscene menu, and will have Boyacky's hand slide on-screen, above the big red skull-shaped button, with a command to "Press Button." Do your best "Pochittona!" and press the button, which instead of causing any sort of self-destruct sequence, will instead simply make the skull button's eyes light up, which enables several things.

First thing you'll notice upon returning to the normal options menu (which you can do by pressing Right on the D-pad again to highlight the cutscene selector again and then press the displayed button to exit), is that the upper limit of credits you can now select has gone from 9 to 50. Starting a new game in either mode will reveal the other effects: A level select, and having the Dokurobei Car unlocked from the start (even in Normal Game, where you otherwise never get to use it!).