A play on the name of the Xbox game "Ninja Gaiden Black."

"Ninja Black" means "he's a ninja clad in black clothing."

http://images4.fanpop.com/image/pho.....54-600-372.jpg

EDIT: I just realized that referring to Doku's armor as "black" and Ryu Hayabusa's clothes as "black" at the same time is bad overall form in this fixed verse poem. XD

Oh well.