Unique in K-pop, AOA is an idol group with a built-in sub-unit: AOA Black, a pop rock band in the vein of their labelmates CNBLUE. In either incarnation, they perform songs with an energetic, retro-tinged vibe, like the funky electric organ chords on AOA's breakthrough single, “Miniskirt” or the soul-inspired piano line that runs through AOA Black's “MOYA". They've also made moves into the Korean hip-hop world, bringing their fresh voices to cool collaborations with rap producers like Primary and Rhymer.