D-Xhird

Pause the game and press XBZ together to enable camera to move around arena.

During a match, when both the health meter and weapon strength meter go down and glow red, press L shoulder + R shoulder buttons at same time.

Hold L-shoulder button + XYZ + Down/Right during games first Now Loading screen (written with gold lettering on a D-Xhird wallpaper) and keep holding buttons down till Dip Switch menu pops up.

You must enter the following code before you can use Karen's Skirt Change code.

During the Title Screen where it says Press Start, hold down the following buttons:
L shoulder + R shoulder + Left + X + B + C
Continue holding them down and press Start button.
If done correctly instead of the regular sword clash you should a hear an echoing sword clash sfx.
Release buttons and proceed to use the Karen skirt change code after this.

Note: This code will last for only one game mode and will not save so you must input it prior to each time you wish to use it.

In order to use Karen's Skirt change without above code:
Beat the game once with Karen to use ABC code freely.
Beat the game with all characters to use XYZ code freely.

When the Now Loading screen appears before match press and hold
A-B-C - Skirt is transparent
X-Y-Z - Skirt is removed

Beat the game with all characters, including bosses and hidden ones, then beat the game using Boy once more. This will unlock the Special ending CG, Boy's History.

Unlock Bosses Venus and Izanagi:
Beat the game once.

Unlock Shadow Boy:
Beat the game and bosses without using continues.

Unlock Eiji Shinjo:
Beat the game, bosses and Shadow Boy without using continues.