Activating this trainer:
Press F1 at main menu.
Listen for 'Trainer Activated'.
Press desired hotkey. All hotkeys can be changed on the trainer.
NumPad2: Unlimited Ammo
NumPad3: Change Coins By 50
NumPad4: Change EXP By 100
Invincible: While active your life will not decrease.
Unlimited Ammo: While active your ammo will not decrease.
Coins / EXP: Make sure your equipped a weapon. Press hotkey and open status screen to see it has changed.
Unlock more trainer options including updates from here - Ultra Despair Girls Trainer