Ninja Assault

Mission mode Chapter 2:
Successfully complete Guren's Chapter in story mode.

Mission mode Chapter 3:
Successfully complete Gunjo's Chapter in story mode.

Mission mode Chapter 4:
Successfully complete Aoi's Chapter in story mode.

Mission mode Chapter 5:
Successfully complete story mode.

Mission mode Final Chapter:
Successfully complete all chapters in mission mode.

Fireworks training mode:
Get the top score in story mode to unlock the Fireworks mini-game in training mode.

Magnum:
Successfully complete the Final Chapter in mission mode to unlock a Magnum in story mode.

Shotgun:
Get an "S" rank in all the bonus training missions to unlock a shotgun in story mode:

More credits:
You can gain one additional credit, up to a maximum of twelve, if you lose all your credits in a chapter.

If you get to the very last Boss of the game on any chapter except arcade, but get "Game Over" while fighting it, you should get a screen that tells you that the number of credits you have has now increased by ten.
G-Sides.

Hint: Easy reload:
This trick requires a controller with an auto-fire feature and the Guncom2. Set up the Guncom2 as usual, then take the auto-fire controller and use it in port one. Set reload to auto-fire. The controller reloads as you do all the hard work.
Stephen R.

Hint: Accuracy saves health:
If you try to empty out your bullets into the enemy's head as fast as possible, this can make you lose more health. Try to limit the speed of your trigger finger . The more bullets you shoot, the more times you have to reload and become vulnerable to being attacked.
Aaroncsmit.

Hint: Fast reload:
Go to "Button Configuration" and set one of the buttons to reload. This way, you do not have to shoot off the screen to reload, making everything easier.
David Wong.