Minako Kotobuki
Toyosaki then performed the opening theme of the 2009 "First Love Limited" series, titled "Future Stream" with Ayahi Takagaki, Haruka Tomatsu, and Minako Kotobuki. Shortly after, the four formed the musical group Sphere. They are affiliated with Music Ray'n, an artist management and publishing group of Sony Music Entertainment Japan. The theme was released as the group's first single on 22 April 2009.