Onimusha 3: Demon Siege Cheats

Easy difficulty:
Intentionally lose the game two times under the normal difficulty setting.

Hard difficulty:
Finish the game under the normal difficulty setting.

Michelle's alternate costume:
Finish the game under the normal difficulty setting.

Michelle's second alternate costume:
Finish the game with an "Onimusha" rank. Alternately, play the game with a memory card with a saved game from Onimusha Blade Warriors.

Jacques' alternate costume:
Finish the game under the normal difficulty setting with a high score as Jacques. You can also finish the game as Samanosuke's alternate costume.

Samanosuke's alternate costume:
Finish the game under the normal difficulty setting with a high score as Samanosuke. You can also finish the game as Jacques' alternate costume.

Panda costume:
Finish secret training mode. Alternately, play the game with a memory card with a saved game from Onimusha Blade Warriors.

Alternate ending sequence:
Increase all seven Haori of Ako to the maximum. This requires all Kodama to be found.

Critical (Issen) mode:
Finish the game under hard difficulty. In this mode, only critical hits can kill opponents.

Devilish mode:
Finish the game in Critical (Issen) mode.

Ultimate mode:
Finish the Oni shooting mini game. The game will start with Sam having the Bishamon sword; Jacques having his best Oni Musou; unlimited arrows, bullets, unlimited Oni power, thirty Medicines, and ten Talismans.

Bishamon sword:
Finish the game with the "Onimusha" rank. Alternately, get the Bishamon sword in the Phantom Realm in Honnouji when Sam goes to the past. To find it, go to the save location at the foot of the stairs to the temple, then look to your upper left to find the hanging man. Approach him to be sent to the Phantom Realm. By collecting eight Red Orbs you will unlock the chest that contains the Bishamon sword.

Oni Musou:
Have Jacques go through the Phantom Realm in Honnouji.

Adventures of Heihachi (Heihachi Buraiden) mode:
Finish the game. Heihachi (Honda) is now selectable.

Genma Puzzle mini game:
Solve all the puzzles in the game.

Secret training mode mini-game:
Finish normal training mode, then complete the game.

Oni Shooting mini-game:
Finish the game under the normal difficulty setting.

Ako's Black Haori:
Finish Issen/Oni training.

How to beat Guard Dog:
REMEMBER: This was done under the normal difficulty setting. First, stock up on magic for all your weapons. Then, stock up on all the Purple Souls. At the beginning, jump behind him after he attacks. Then, just waste the magic on him. Use every weapons magic until you do not have any more. After that, use regular attacks. Watch out for the ice attack. Most of the time the thunder magic from him is off target. After a few regular attacks, transform into the Onimusha and attack him hard. However, do not use the mega attack yet. After a few attacks, just before your magic runs out use the mega magic attack on him. If he is not defeated, then just attack him a few more times.

How to beat Two Marquless:
When playing as Michelle, go further behind near the skull door and throw some grenades on them.

Kill all Genma onscreen:
This can be done without charging during an Onimusha. Also, block Issen works during an Onimusha and takes out all enemies.

Regain health:
Equip Ako's White Haori then stand still.

Hidden Secret Medicine:
When you are helping Michelle save her comrades, keep pushing the ball as far as possible. You will see a light in the water.

Awards:

Bravery: Finish the game without saving.
Critical: Kill over 40% of your enemies with critical hits.
Defense: Take less than 5,120 damage.
Explorer: Find all 23 Tengu chests.
Offense: Kill over 3,000 enemies.
Speed: Have a completion time of less than 5:00:00.

Onimusha 3: Demon Siege Official Website