Amy and Rika are 2 best friends who met at a small company called HeartBeat Entertainment. They successfully debuted as K-pop idols in a group called "BEETHART". Amy is a Korean idol who is the main vocalist of her group, she is predominantly known for her excellent vocals and her vivacious personality. Rika on the other hand is a Japanese foreigner who debuted along in the group. At first, Rika struggled to communicate with the other members because she had minimal knowledge of Korean, but she steadily improved overtime as she continued studying more about the language. Rika and Amy gradually grew closer as they started communicating more frequently.