Nishino Yuuna is an ordinary girl who lives in Shirakaba city that is known for it’s music talents and elite Avenir Music School. Though she knows nothing about music, she enjoys listening to daily practices of Avenir students she can hear through the windows of library she works at. But one day Yuuna's called to become a teacher of a group full of genius troublemakers from a special class R known as W6(The Bad 6). Her goal is to make at least one of them graduate in a period of year. And so, her new life starts...