Unlockable: Bonus Art & Character Art - Complete the game on Devil hunter difficulty (may also unlock by beating on Human difficulty).
Unlockable: Son of Sparda Difficulty - Complete the game on Devil hunter difficulty.
Unlockable: Gallery - Complete the game on Devil hunter difficulty (may also unlock by beating on Human difficulty).
Unlockable: History of Devil May Cry - Complete the game on Devil hunter difficulty (may also unlock by beating on Human difficulty).
Unlockable: Bloody Palace Survival Mode - Complete the game on Devil hunter difficulty (may also unlock by beating on Human difficulty).
Unlockable: Full Ending - There are technically two endings in the game. To see the "extended version" of the ending, you must protect the character Kyrie from being damaged for at least a minute and a half as the credits run. If you manage to do this, the rest of the ending is thereafter revealed. Otherwise, you’ll have to beat the last boss once more and try again.
Unlockable: More Difficulty Levels - There are three "elite" difficulty levels that can be unlocked in the game. Once you’ve unlocked Son of Sparda mode, you can play through it. If you get through it, two more difficulty levels will be unlocked -- Dante Must Die and Heaven or Hell. If you get through either of those subsequent difficulty levels, you will unlock the final difficulty level -- Hell or Hell.
Unlockable: Super Nero & Dante Costume - To unlock the Super Costumes for Nero and Dante, beat the game once through on Dante Must Die difficulty.