Kuroko / 黒子

Kuroko (kurogo) are people who wear black costumes and black hoods on the stage of traditional Japanese performing arts such as Kabuki and Bunraku, and who perform backstage tasks such as assisting actors and operating stage equipment.
The term is also used as a metaphor for behind-the-scenes figures who support organizations or individuals without appearing on stage.

黒子（くろこ/くろご）は歌舞伎・文楽といった日本の伝統芸能の舞台で黒装束・黒頭巾を着用し、役者の介添や舞台装置の操作など裏方の仕事を担う人のことです。

また表舞台には出ず、組織や個人を支える裏方的な存在の比喩としても使われます。