Successfully complete the game with no cheat codes enabled and any desired costume with an "AAA" score to unlock View mode.

Successfully complete the indicated task to unlock the corresponding costume:

Apron Dress: Successfully complete the game on the Easy difficulty.
Business Suit: Successfully complete the game. Note: The costume is in the left-hand locker room in the CTI Building.
China Dress: Successfully complete the game on the Normal difficulty.
Knight Armor: Successfully complete the game on the Deadly difficulty.
Lightning Custom: Successfully complete the game and have at least seven stamps on the Square-Enix Member site.
OD Suit: Successfully complete the game and have at least one stamp on the Square-Enix Member site.
Santa Soldier: Successfully complete the game. Note: The costume is found by going down the stairs to the lockers in Maeda's Base, and searching the one on the left.
Swim Wear: Successfully complete the game on the Hard difficulty.
Titanium Bunny: Successfully complete the game on the Genocide difficulty.

Successfully complete the game twice to view an extra scene after the credits.

Successfully complete the game fifty times to unlock the shower scene in the "Video Log" menu. View the scene in the Video Log ten times to be able to change the camera angle to her back.

Start a New Game+ mode game. To unlock both cheats at no cost, unlock them using your BP, then reload the same New Game+ mode saved game without saving first. The game will resume with your original amount of BP, and the cheats will remain unlocked.

At the main menu, press Up(2), Down(2), Left, Right.

Use a spear to break their armor first, then attack them with whatever desired. The gray bar is their armor amount. When fighting the second Giant Immortal, he will run away and start to regain health. Go to the statue he is beside, then push it on top of him to eventually defeat him.