This is the fourth anime series of Pretty Rhythm. The story features a girl named Lala Manaka, who desires to become an Idol. To further her debut the best, the three main protagonists from the previous Pretty Rhythm series Aira, Mia, and Naru give her lessons about how to be the best Idol. In addition to the lessons she's learning, the series also retells the events of the previous Pretty Rhythm series.
(Source: Pretty Rhythm Wiki)