noun
hidden highlights; peekaboo highlights; underlayer hair dyeing
A hair coloring technique where only the inner or underlayer of the hair is dyed, so the color peeks out subtly. A wasei-eigo term from 'inner color'.
wasei-eigo (Japanese-coined English), from inner color
インナーカラーを入れると、髪をかき上げたときにちらっと見えておしゃれです。
When you get hidden highlights, they peek out stylishly when you push your hair back.
彼女のインナーカラーはピンクで、とてもかわいい。
Her hidden highlights are pink and really cute.