Kisaragi was a music superstar in her youth before becoming a singing coach. After being tragically separated from her three daughters, she adopted Reika and became her mentor. After deciding that Reika has learned all that she can from her, Kisaragi opens a music school and picks the best students for a special "Class S". It is revealed in the latter part of the series that the three heroines and the girls who enter her special Class S of her music school and form the R3 vocalist trio ; Akari, Yuki, and Nozomi are her long lost daughters. (Source: Wikipedia)