Defeat Dracula and his final form in the 8th stage with Richter.
Note that there is a "cheap" way of getting this trophy. I do not know if it's a glitch but... you can unlock this trophy by watching the "Boss demo" video strategy of defeating Dracula. It's actually how I got the trophy. You must spend 400 in-game cash to buy the video. But to be able to buy the video, you have to reach the 8th stage. At that point, you could actually try to finish the game, it's not that hard... but I just wanted to let you know that there is another way!
I was honestly shocked that it unlocked at the end of the video!