Erick

Erick is the final boss of the game.

He is introduced in Aquarium City, before your fight against Richard.

You will only find him again at the end of the game, and you will have 4 minutes to defeat him before The Violatifier activates.

His ability is to never give up. That coincides with demons being killable only after their determination wimps, and how people turn into monsters if they get obsessed with anything.