Chika keeps trying to get Riko to join the School Idol Club, only to get rejected every time, while Dia shows a surprising amount of μ's knowledge. Hearing about Riko's struggles with piano playing, Chika and Yō take her scuba diving, where she learns to hear the sounds of the ocean. The next day, Riko decides to help Chika composes their music, encouraging her to write lyrics based on her love of idols. After listening to one of μ's' song's, Riko decides to take up Chika's offer and join her club. (thetvdb.com)