Pl@net sphere, officially スフィア, is a Japanese idol unit consisting of Minako Kotobuki, Ayahi Takagaki, Haruka Tomatsu, and Aki Toyosaki (寿美菜子, 高垣彩陽, 戸松遥, and 豊崎愛生), four seiyuus with Sony's Ray'n agency. The group debuted in April 2009 releasing their first single "Future Stream". As all four are voice actresses, their music is frequently featured as tie-ins to a variety of anime series. (Not to be confused with SPHERE of INFLUENCE (スフィア・オブ・インフルエンス).)

Read more about スフィア on Last.fm.