The story
Borrowed from Japanese slang ガングロ (ganguro), from 顔 (gan, “face”) 黒 (kuro, “black”), in reference to the style of makeup intended to imitate a dark tan.
Etymology from Wiktionary, CC BY-SA 4.0.
ganguro
Today it means: A Japanese girl fashion trend involving dyeing the hair and tanning the skin. Full definition →