Minako Kotobuki is a Japanese seiyuu and singer from Hyogo Prefecture, Japan. She is best known for her role in K-On!. Her career as a musician began with her performance of the opening and ending themes of the anime series K-On! in April 2009. In the same month, she and three other voice actresses debuted as the musical group Sphere with their single "Future Stream".
Kotobuki began her singing career with the performance of the opening and ending themes of the 2009 anime series K-On! with fellow voice actresses Aki Toyosaki, Youko Hikasa, and Satomi Satou. Shortly after, she performed the opening theme of the 2009 Hatsukoi Limited series with Aki Toyosaki, Ayahi Takagaki and Haruka Tomatsu. The four are affiliated with Music Ray'n, an artist management and publishing group of Sony Music Entertainment. They are currently known as the musical group Sphere and released their first single "Future Stream" on April 22, 2009.