Successfully complete the game under the normal difficult setting. Then, hold L while selecting the "New Game" option at the opening menu. Successfully complete the game under the very hard difficulty setting to unlock yet another costume.
Beat level three boss
Some players tend to have trouble with this boss mainly because of his massive power on attacks. Basically, he's equipped with a gigantic electric gun, that shoots out blasts of electrical charges in small intervals. What you should do is keep distance between him and yourself. Keep running in circles, but DO NOT jump (makes you an easier target). You can try rolling, but keep running in circles until he fires about 5 laser blasts. Suddenly, his gun will discharge, and it'll be jammed for a few seconds. Quickly sprint in, and lay down a few power slashes. If you want, you can also cast Ninpo magic to assist in causing more damage. Just repeat this strategy, and keep retreating/approaching. If you stay close too long, he'll grab you, and shoot you point blank with the weapon. Also, try to keep several potions on hand when facing him. You might take a few hard hits along the way. Aside from that though, he's not as challenging when compared to other bosses faced.
Breathe Underwater
Approach a large body of water and just as you hit it tap A to run on the water. Keep running until you hit a wall and start sinking slowly. Eventually you will hit the bottom and if you keep running you will be able to breathe underwater.
Classic Ninja Gaiden 3: The Ancient Ship Of Doom mini game
Get a "Master Ninja" rank in all levels under the hard or very hard difficulty settings.
Dark Dragon Blade
Start a new game with an already completed save file. Visit Muramasa's shop in Chapter 13 to find the blade.
Defeating Zombies
Use the diving Y attack that takes off their head. It will not kill them, but they will be blind.
Easy Boss #1
The first boss you come to which is murai. You can't really attack head on. So go to one of the walls and face the wall and wait for murai to get close. Then do a wall run straight up the wall bye pressing A and then holding up on the anlog stick. Once you are above his head press A to jump off the and right after jumping off press X to deliver an attack to murai. Then as soon you reach the ground roll away. This won't always hit murai he'll dodge it sometimes. But the attack will hit about 70% of the time. Just keep repeating this process for an easy win.
Easy Cash
Did this at the Clocktower in Tairon, but I'm sure it should work at any store. Simply go up the set of stairs marked by the blue border, and take care of the three enemies in the stairway. Now, go back down the stairs and return back up to kill the same three guys again. Collect the loot or health and repeat as desired! I found that if you use the Nunchaku, you can score around 30 or 40 hit combos, giving you up to 1,000 cash points at a time.
Easy Ninja Gaiden 2/3 Trilogy Games
After getting access to Ninja Gaiden, play the game on very hard. When on Chapter 4 and you're in the Clock Tower Plaza you will see a door with a pink jewled eye. Above it will be a platform with a chest. Make you way up to the chest. Once there turn around and you should see the Clock Tower. Shoot the face of the clock with your arrows and another chest should appear next to you. Open to find (Ninja Gaiden 2: The Dark Sword of Chaos). Ninja Gaiden 3: The Ancient Ship of Doom is in Chapter 10. Once you enter the Hall of Balance. Enter the door (not the one behind the waterfall) and when you get into the room run to the right and inbetween the two podeums do a Flying Bird Flip to reach the top. There you will find Ninja Gaiden 3 rather than the previous Scarab that was there. Whoever said you had to get Master Ninja in every level should have wished they known this !
Evil Ryu
Complete the game on Very Hard.
Finishing kill
While a foe is on the ground, walk up to it and press Y. This will instantly kill almost any foe.
Futuristic Outfit
Complete the game on Normal or Hard difficulty and start a new game while holding L.
How to beat 2nd boss
To beat the second boss you need the art of the inferno. Your just run up to him and jump and press y to stab down at him and keep repeating the Art of Inferno. The Art of Inferno should be equipped if not equipped, or it could equip automatically. Now you have to chop him up a little bit more until you beat him.
In-game reset
Press Start + Back during game play to return to the main menu.
Keep the Original Blue Ninja Costume
Highlight "New Game" and hold down the L + R triggers and press the A button. You will hear a scream to confirm entry. You will now keep the original blue costume that Hayabusa starts with beyond the second chapter.
Kill enemies quickly
To kill an enemy very fast, jump towards them fairly close using A, then quickly tap Y immediately before you hit them. You should either throw them with the guillotine throw or slice their heads off. If they keep trying to get off the ground, tap Y again to pin them down or cut their head off. This is useful when you need some extra money, are almost dead, or when you just simply want to get through the section quickly because of frustration.
Kill Rachel
This is a neat little thing I found. It turns out that you can kill Rachel when she's hanging above the pyramid before Alma V2, or in the volcano cave before Evil Murai. Just shoot her with an arrow and you'll get a game over.
Movie Gallery
Beat the game on Normal or Hard to unlock all CG movies.
Ninja Gaiden I Passwords
Act I: L, X, A, Y, A, X
Act II: A, X, X, R, Y, A
Act III: X, Y, B, R, L, X
Act IV: B, R, A, B, Y, Y
Act V: X, A, Y, X, L, L
Act VI: R, Y, R, L, A, X
Ninja Gaiden II Passwords
Act I: A, A, B, X, Y, R
Act II: X, L, R, B, B, A
Act III: L, Y, B, A, R, R
Act IV: A, L, X, Y, Y, B
Act V: R, A, A, B, X, L
Act VI: Y, L, R, A, Y, R
Act VII: B, B, X, Y, A, L
Ninja Gaiden III Passwords
Act I: B, Y, R, L, X, A
Act II: A, R, R, Y, A, L
Act III: L, B, R, Y, L, Y
Act IV: R, R, B, A, Y, X
Act V: Y, A, B, X, R, X
Act VI: B, X, X, A, X, Y
Act VII: X, R, X, Y, Y, L
Plasma Saber
Beat the game on Normal to unlock a new costume and plasma saber (Luke, you are now a ninja). To use the new costume, hold down the LEFT TRIGGER and select New Game.
Play Japanese Versions of Classic Ninja Gaiden Games
Put the Text and Subtitles to Japanese from the Options menu, and you can play the Japanese versions of the first 3 classic Ninja Gaiden games "Ninja Ryukenden".
Retain Health with Kitetsu
While using the Kitetsu sword, equip the Tranquility Bracelet--earned by finding 40 scarabs--to counter the health drain effect of the sword.
Run on Water
Anywhere there is water, simply walk Ryu onto the water and then repeatedly tap the A button to run across the water.
Skip Cut-Scenes
You can skip most of the cut-scenes in Ninja Gaiden by pressing START, A, START.
Special attack
Press Y + B to unleash a super attack that will seriously hurt anyone.
Ultimate Wooden Sword
You must buy the wooden sword first and then rack up the essence to upgrade it completely (a little over the 99,999 essence you can hold at once so make a couple trips) it will change into something called "unlabored flawlessness". It will kill anything besides a boss with 2 good whacks.
Unlock Classic Ninja Gaiden 2: The Dark Sword Of Chaos mini-
Get a "Master Ninja" rank in all levels under the normal difficulty setting.
