Unlockable - After Game Clear (JP) |
| Easy Mode | Get killed and continue 3 times and ''Easy Mode'' will be added the next time you Game Over. |
| Issen One Flash Mode | Clear Oni Organization mini game. Very hard: Enemies will only receive damage if you hit them with One Flash attacks. |
| Oni Organization (mini game) | After game clear |
| Puzzle Illusion Dream Dimension (mini game) | Unlocked by clearing the game with all the Paintings of Beauties collected. |
| Hard Mode | Added after game clear with Normal Mode. |
| Strongest Equipment Mode | Added after game clear with Hard Mode. Begin with Blazing Fire Sword, money x 20,000, Intense Medicine x 30, Wood that Dies for You x 10, all armors Lv3, bullets unlimited, arrows unlimited, and skill gauge won't decrease. |
| Scenario Route | After game clear |
| Man in Black Suit (mini game) | After game clear |
| Leather Suit | Clear game with ''Onimusha'' rank to unlock the Leather Suit. |
| Oyuu Costume Change | Accomplish 100% Scenario to unlock an extra costume for Oyuu. |
| Unlock Easy Mode | Simply die three times in a row. You will then open ''Yasashii'' Mode. You must go to the main menu and select the ''Tokuten''. Now simply go to the difficulty settings, choose Easy. |
Unlockable - After Game Clear (US) |
| Unlock Puzzle Phantom Realm Mini-game | Collect all 18 artworks in the normal game and then complete it to unlock Puzzle Phantom Realm mini-game in the ''Special Features'' menu. In this game mode, there are no enemies. |
| Unlock Critical Difficulty | Complete the Team Oni mini-game once to unlock Critical difficulty level in the ''Special Features'' menu. In this difficulty, you can only kill enemies with a critical hit. Plus, Ultimate Mode is disabled. |
| Unlock Extra Jubei | Acquire the Fashionable Goods item and complete the game with an ''S'' ranking to unlock Extra Jubei in the ''Special Features'' menu. Use L2 to equip. |
| Unlock Extra Oyu | Play the game repeatedly and make good alliances with the sub-characters until you acquire 100% of the scenarios in Scenario Route. Extra Oyu will be unlocked in the ''Special Features'' menu. |
| Unlock Easy Difficulty | Die three times in the game and Easy difficulty level becomes available in the ''Special Features'' menu. |
| Unlock Hard Difficulty | Complete the game on Normal difficulty to unlock the Hard difficulty in the ''Special Features'' menu. |
| Unlock Ultimate Mode | Complete the game on Hard difficulty to unlock Ultimate Mode in the ''Special Features'' menu. Toggle Ultimate Mode on to start a new game. Rekka-Ken sword, unlimited arrows, unlimited bullets, 30 Perfect Medicine, 10 Talisman, unlimited magic, and more. |
| Teaser FMV (the preview movie of Onimusha 3), The Man in Black mini-game, and Team Oni mini-game. | Complete the game for the first time. |
| Issen Mode | Clear Team Oni (mini-game). This is the toughest difficulty. Even though the enemies and bosses can be damaged, they only can be killed off with a ''issen'' (critical hit). |
| Mind Twister Mode | Clear the game, and collect all 18 artworks. |
| Unlock Onimusha Team Mode | Beat the game at least once to unlock this mode. This is a special mini-game that enables you to play a variety of characters through several previous sections of the game. |
