Kuroko

Over time the unvoiced mispronounciation 'kuroko' also started to be used, and needed its own spelling that took the simple 子 ko character as an 'ateji' (sound only), making the 黒子 kuroko word.

Kuroko wear all black, head to toe, in order to imply that they are invisible and not part of the action onstage.

The convention of wearing black to imply that the wearer is invisible on stage is a central element in bunraku puppet theatre as well.

Kuroko will wear white or blue in order to blend in with the background in a scene set, for example, in a snowstorm, or at sea, in which case they are referred to as "Yukigo" (雪衣, snow clad) or "Namigo" (波衣, wave clad) respectively.

The theatrical convention of dressing ninja characters as apparent stagehands to imply stealth and to surprise audiences contributed to this popular image, in contrast to the historical reality that real ninjas usually dressed like civilians.