The back of the neck is a sensual area in traditional Japanese beauty standards. For geisha and maiko, leaving that bit of the neck unpainted also adds to the sense of mysteriousness that comes from wearing the "mask" of white makeup. It emphasizes that there's a real person under the makeup whose features are obscured but not quite hidden by it.
Anna's Asian Art Print Paperie1_4
Asian Symbols1_5 (both retired)
