Ninja

Ninjas are a variety of Grunt Enemy who appear in Asian Town and Casino Land.

Standard Ninjas
They are typical depictions of Ninjas, who wear almost entirely black outfits consisting of a long cloth wrapped around their heads to make a mask, sleeveless tank tops, rings on their arms, long fingerless gloves, a martial arts belt, a pair of puffy pants, and a pair of boots.

Elite Ninjas
Elite Ninjas are recognizable by their theatre masks, which depict Kitsunes, and wear similar outfits to the standard ninjas, however, their outfits have flame patterns on the shirt and pants.

Motorcycle Ninjas
Motorcycle Ninjas wear almost the exact same outfit as Standard Ninjas, with the exception of their motorcycle helmets, as their name indicates, they ride motorcycles, which have a durable looking build with the design of a Kitsune on them.

Description
Ninjas are a quick and agile combatants appearing in the Bistro in Asian Town. Aside from their unique appearances, they are distinguished from other grunts by their unique set of animations, as well as their preference of using sneak attacks by jumping out from beneath Tatami mats, busting down Shōji doors, and dropping down from the ceiling.

They come in three versions, the Standard ones, who look, act, and fight like typical Ninjas, the Elite ones, who are distinguished from their subordinates by their Kitsune masks, as well as their ability to throw explosive darts, and the Motorcycle Ninjas, who primarily attack by trying to run over and batter Jack with their bikes.

They have a strong hatred of pirates, to the point where if they see something that even reminds them of a pirate, such as the hats that they wear, they will drop everything to hack it to pieces with their swords.

The Ninjas are unique among enemies in that they will never attack eachother on purpose, implying they work on the same team, which could possibly also consist out of Tengu and Shogun as well, given that Tengu is one of their own and a small team of Ninjas will attack Jack before he fights Shogun.

Trivia

 * As a whole, they are notably disliked by Kreese Kreely, who states that he has gotten hard-wood floors to prevent sneak attacks from them, which means he could possibly be afraid of them due to him taking precautions against them, or that they could collectively hold a grudge against him for some reason.
 * Their inclusion in the game might be a reference towards how action movies in the vein of Kill Bill often use Ninjas as easily killed or defeated canon fodder to establish the strength of the protagonists.
 * Their hatred of pirates is a reference to the long-lasting pop culture joke of pirates versus ninjas.