Even kooky ninjas know that it only makes sense to wear a mask! The one in yellow told me that you will catch a shuriken to the throat if he sees you out in mixed company without one, so be on your best behavior, germ-spreaders!
Vengeful, Azure and Cold Ninjas all agree! They come with a nice selection of alternate heads, but you have to keep it safe.
Red and blue (azure) is a homage to the video game character Ryu Hayabusa from Ninja Gaiden based on the original NES game
Yellow is a homage to the video game character Scorpion from Mortal Kombat.
A second homage can be found combining parts from Vengeful Ninja and Azure Ninja to create Enter the Dragon bloody Bruce Lee.
Cold ninja is a homage to the video game character Sub-Zero from Mortal Kombat and his younger brother starting from Mortal Kombat II