Unlockable: New Outfits
To unlock the outfits below, fulfill the requirement listed.

Camouflage - Beat the game once through on Warrior difficulty
Jaguar - Beat the game once through on the Path of the Mentor difficulty
Red Gear - Beat the game once through on the Acolyte difficulty

Unlockable: Old Film Filter
To unlock a filter that will make the game appear to be an old film, beat the game once through in its entirety.

Unlockable: Music Player
To unlock an in-game music player where you can listen to all of the game’s music in one place, beat the game once through in its entirety.

Unlockable: New Game+
To unlock a New Game+ option, beat the game once through in its entirety, being sure to save your game after watching the ending and credits.

Hint: Weapon Locations
Below are a list of some of the weapons in the game, and where in the game they can be acquired.

Dragon’s Claw & Tiger’s Fang - During the fourth chapter, you will find these weapons in a glass display case in the first room at the Statue of Liberty’s base.
Dragon Sword - Your default weapon.
Eclipse Scythe - Once you defeat Volf, the boss during chapter six, you will acquire it.
Falcon’s Talons - During the second chapter, right before you head to the Dragon Shrine, you will see another building. Kill the ninjas there to acquire this weapon.
Kasari-Gama - During the fifth chapter, a dead ninja will be holding this weapon on the second bridge you encounter on your right.
Lunar Staff - About 60% through the first chapter, a statue in a shrine will be holding the weapon.
Tonfa - During the seventh chapter, a dead ninja is holding this weapon in the storage room that you drop into about 70% through the stage.

Hint: Yellow Essence Exploit (Chapter Six)
This exploit works during the sixth chapter, entitled The Lycanthropes’ Castle. After you fight the Giant Skeleton miniboss, you will be thrust into a battle with more Scorpion Skeletons. Fight them and wall run up to the next floor thereafter. Then, drop back down, fight them again, and repeat this process as much as you’d like for an infinite number of Yellow Essence.

Hint: Yellow Essence Exploit (Chapter Two)
Here’s a great way to farm Yellow Essence during chapter two. After ridding the bridge you encounter of all of the archers and acquiring the Crystal Skull there, you will have to continue down another wooden path. This will lead to a pair of chasms that you have to swing over to get to the save point. Below that is a lower walkway full of enemies. Kill them all, and then scale a nearby ladder to reach the upper area again. When you go back down, the enemies will have respawned. You can kill them again to grab their Yellow Essence, climb back up, jump back down, repeating this ad infinitum to get all the Yellow Essence you want.

Hint: Yellow Essence Exploit (Chapter One)
The following yellow essence exploit can be completed on the game’s very first chapter, and is especially useful when playing on Master Ninja difficulty. Before and after crossing the bridge, you’ll deal with enemy ninjas (it’s the bridge where the first God of Life and a treasure chest can be found). After you cross the bridge, defeating ninjas as you go, head towards the middle alley that brings out two more ninjas on foot and another two ninja archers. Run back and charge up to Ultimate Level 2. Continue to run back and forth, and the ninjas will keep respawning and coming at you. If you have the skill, getting away with $40,000 while having 50%-75% of your health still available to you is a possibility.