At the Title screen, press Up, Trianlge, Left, Circle, Down, X, Right, Square.
Play as Copain
Complete the game with Femme.
Play as Hardi
Complete the game with Copain and Ciel with the top money rank as those characters. After that beat the game with Rival to unlock Hardi in survival and time-attack mode.
Play as Rival
Without losing to Rival, complete the game with Ciel.
Scene Select Option
Complete the game with all four characters.
Survival Mode Option
Complete the game with Copain with the top money rank.
Time Attack Option
Complete the game with Ciel with the top money rank.
Unlock Everything
At the title screen hold L1 and R1 and press Circle, Square, Up, Circle, Triangle, Down.