Riko (莉子)'s Links
Riko has a barely-concealed crush on Hibiki.
Hibiki is one of Rouko's friends, so she is familiar with Riko. She thinks Riko is a cute little kid.
Riko is Rouko's younger sister. She sees Rouko as very mature and ladylike and strives to be like her.
Rouko is Riko's older sister. They bicker sometimes, as all siblings do, but they care for each other and would do anything for each other.