Hinashi, Koyuki

氷無小雪

An emerging idol whose CD "reached the top of the charts in just one week." She is Yuu's childhood friend. She calls Yuu "Niko-kun," and he refers to her as "Tama-chan."
Fuuka is a devoted fan of her music, to the point that listening to one of her songs moves her to tears. One of Koyuki's songs served as the theme for a popular movie ("Half & Half," a clever nod to another manga by the same creator.)
Although his sisters tease him, claiming she would never reply if he reached out now that she is famous, she actually sent Yuu a message on Twitter.