These are ways of opening different Zones:
U1 Zone:
Successfully complete the game on the hard difficulty setting with 90 AP and without using any continues.
U2 Zone:
Successfully complete the game on the hard difficulty setting with 60 AP.
U3 Zone:
Successfully complete the game on the hard difficulty setting with 50 AP.
U4 Zone:
Successfully complete the game on the normal difficulty setting with 90 AP and without using any continues.
U5 Zone:
Successfully complete the game on the normal difficulty setting with 60 AP.
U7 Zone:
Successfully complete the game on the hard difficulty setting without using any continues.
U8 Zone:
Successfully complete the game on the normal difficulty setting.
U9 Zone:
Successfully complete the game on the normal difficulty setting without using any continues.
V5 Zone:
Successfully complete the game with 60 AP.
Inner Level A:
Successfully complete the game with 60 AP (with invincibility, all weapons at level 9).
Inner Level B:
Successfully complete the game on the hard difficulty setting with 90 AP (with unlimited special attacks, all weapons at level 3).
Inner Level C:
Successfully complete the game on the normal difficulty setting (with highest speed, all weapons at level 9).
Inner Level D:
Successfully complete the game on the normal difficulty setting with 90 AP (with five-way attack, all weapons at level 9).
Inner Level E:
Successfully complete the game on the hard difficulty setting (with improved speed when moving up, down, left, right, all weapons at level 9).
Control loading screen:
Press the D-pad or Analog-stick at the loading screen that features the red squares to change their location.