Pre-ordering Metal Gear Rising: Revengeance with Amazon in North America will provide you with an Inferno Armour skin. This dashing red outfit holds more than superficial value, giving Raiden a stat boost too.
Wearing Inferno Armour will allow the white-haired ninja to hold more throwing weapons. This means a greater number of grenades can be equipped, giving you greater opportunity to leave an explosive mark on your foes.
Here's a video promoting the armour: