Onimusha 3: Demon Siege

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

Hard difficulty:
Successfully complete the game under the normal difficulty setting.

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

Michelle's second alternate costume:
Successfully complete 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:
Successfully complete the game under the normal difficulty setting with a high score as Jacques. Alternately, successfully complete the game as Samanosuke's alternate costume.

Samanosuke's alternate costume:
Successfully complete the game under the normal difficulty setting with a high score as Samanosuke. Alternately, successfully complete the game as Jacques' alternate costume.

Panda costume:
Successfully complete 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:
Successfully complete the game under the hard difficulty setting. In this mode, only critical hits can kill opponents.
.

Devilish mode:
Successfully complete the game in Critical (Issen) mode.
Kastro187420.

Ultimate mode:
Successfully complete 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.

Original Onimusha: Warlords swords (Japanese version):
Successfully complete the game with all three items from the Phantom Realms. Then, start a new game to have all three swords from the original Onimusha: Warlords.

Alternately, play the game with a memory card with a saved game from Onimusha: Warlords.

Bishamon sword:
Successfully complete 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. Collect eight Red Orbs to 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:
Successfully complete the game. Heihachi (Honda) is now selectable.

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

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

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

Ako's Black Haori:
Successfully complete Issen/Oni training.

Skip FMV sequences:
Successfully complete the game. When playing the game again, press Start to advance past any intermission sequence.

Hint: Defeating Guard Dog:
Note: 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.
lowsure.

Hint: Defeating Nobunaga:
When you are fighting Nobunaga when he is in his demon form, press Square(2), Triangle. This is a great combo move, but do not overdo it with him. When you absorb the darkness from his sword and you get it, remember that some of his moves cannot be blocked (such as the charge and the fireball moves). You can only block one or two. For the charge move, press Triangle at the last moment when he is on fire and you should dodge it. For the fireball move, just have enough space to run around.
Shinobi5.

Hint: Defeating Two Marquless:
When playing as Michelle, go further behind near the skull door and throw some grenades on them.
Thundark.

Hint: 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.
Nick.

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

When Ako's wearing the White Haori, rotate the Right Analog-stick . Ako will move faster to regain health quicker, depending how fast you can rotate. Note: Do not not use it while you have five Oni Orbs.
Thundark.

Hint: Deflecting critical hits:
Repeatedly tap Guard until someone hits you. And as soon as you see the flash, tap Square. Keep tapping Square to go from enemy to enemy, racking up multiple critical hits.
aMUSEd.

Hint: Bypass Dark Realms:
Any of the three Dark Realms can be easily bypassed. This requires some skill, Ako's Purple Vest, all weapons for the character, and all weapons been completely enhanced. Whether or not the gauntlet is completely enhanced is irrelevant. Before entering the Dark Realm, equip either Chigo (for Samanosuke) or Hyosai (for Jacques). The enemies that attack will appear in multiple waves. Just wait for all enemies to appear, then execute one magic attack. Absorb all the souls that appear. Ako's Purple Vest should allow you to do this as many times as necessary. However, if you are fighting large demons, you may need to get up close with either the Tenso (for Samanosuke) or the Enja (for Jacques). Note: A crucial part of this strategy is absorbing the souls. If you feel that you need Ako's Blue Vest as well, make sure to switch back and forth as appropriate. Also, it is much easier to go straight for the bottom part of the Dark Realm that you are in, as the tougher enemies are down there first. By doing this, you can use your magic efficiently on the tougher enemies and not have to worry about the weaker ones.
Eschex.

Hint: Unlimited Genma Souls:
After going through the first set of double doors where the Oni Army is fighting the Genma, before using the Firefly to go up the short cliff, have the Genma and and Oni Army men on the wall of the short cliff and you as close as possible to the doors on the other side of the field. The supply of Genma infantry are infinite and Oni Army can take care of them by themselves. While they are fighting and nowhere near you, tape down Circle and allow the game to run. The souls will come to you, and you can get as many as desired without interruptions from the Genma. For a slightly faster collection, have Ako's Blue Vest equipped. Note: The process of getting a lot of bars filled of souls will take a long time. Also, when the soul count reaches 9,999, release Circle. This gives you an additional bar (or perhaps more) filled automatically. Then, tape Circle again. Given enough time you can have 99 bars worth of souls.

Note: This trick only works for Samanosuke. Once you obtain the Ten-Point Slash Training Scroll, play under the beginner difficulty setting multiple times. Each time you finish, you should come away with one bar, or close to it. Do this until you have the desired amount of souls, or until you max all your equipment.
Kastro187420.

Hint: Use less magic during magic attacks:
This trick requires the gauntlet for Sam/Jacques to be at least level 2. Charge up the gauntlet (press R1 firmly) to at least two and unleash a magic attack. With the purple vest on Ako you can do about five magic attacks in a row instead of four.
Ken Cheung.

Hint: 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.
michael hazle.

Hint: Easy Red Souls:
Ako's Red Haori is required this trick. When you get to the port town of Sakai and the demons come out to play, equip Ako's Red Haori. Start killing demons with Issen or Block Issen. Clearing each area of demons should give at least three quarters of a full soul bar. The port area is most lucrative (one full bar every time because of the fish demons). The Issen is not necessary, but it is most effective. You can upgrade all of you present weapons to full with this trick, since one level 2 weapon/equip requires about ten bars to level up to maximum.
weberkki.

Hint: Jacques: Oni bind kick:
Grab an enemy with Oni-bind as Jacques and press X. Jacques will reel himself close to the ensnared demon and kick it to the ground. Note: This does not work on large enemies -- ONLY the smaller Genma.
weberkki.

Hint: Awards:

Bravery: Successfully complete 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.

Glitch: Spinning Samanosuke and Jacques:
Let the Jelly monster's babies grab you then press R1. You will spin around. Also, press R1 when you are surrounded by them.
Thundark.