The following is a list of unlockable characters and features. Complete the game once to unlock Special mode on the main menu, from which you can review any CGs, endings, and voices you unlock through the methods below.

Unlockable	How to unlock
Unlock Character CGs and Endings	Complete Arcade mode with each character
Unlock Extra Neco-Arc Voices	Complete Survival mode with Neco-Arc (do this 6 times to unlock all Neco-Arc voice samples).
Unlock Neco-Arc	Complete Arcade mode with all 20 non-secret characters (press START when highlighting Arcueid to select Neco-Arc).
Unlock Neco-Arc Chaos	Complete Arcade mode with Neco-Arc after unlocking all Neko-Arc Voices (press START when highlighting Nrvnqsr Chaos to select Neco-Arc Chaos).
Unlock Omake (Extra) Voices	Complete Survival mode with each character.
Unlock Special System Voice	Complete Survival mode with Hisui & Kohaku (the tag team character).