At the "How To Play" screen, press Left, Right, Left, Right(2), Left, Right, Left.
At the character selection screen, highlight the following characters (in order) and press X before moving on to the next person (a sound will be heard each time X is pressed): Terry, Hon Fu, Mai, Geese, Bob, Sokaku Mochizuki, Andy, France, Joe Higashi, and Blue Mary. If you entered the code correctly, the portrait for Ryuji and the Jin twins will appear on the character selection screen.
