The central aspect of the plot for The Idolmaster deals with the training of prospective pop idols on their way to stardom. The main talent agency featured in the series is 765 Production (765 Pro), a rising studio located in a small office. Other studios include 876 Production (876 Pro), 961 Production (961 Pro) and 315 Production (315 Pro). At 765 Pro, there are initially 10 idols the player can choose: Haruka Amami, Chihaya Kisaragi, Yukiho Hagiwara, Yayoi Takatsuki, Ritsuko Akizuki, Azusa Miura, Iori Minase, Makoto Kikuchi, and Ami and Mami Futami (who work as a pair). Three additional idols later added to 765 Pro include: Miki Hoshii, Hibiki Ganaha and Takane Shijō.
A recurring theme in the series emphasizes the struggles an idol must go through to achieve stardom. This is indicated by the level of an idol's tension meter.] Games in the series also explore relationships between characters, ranging from the relationship that develops between an idol and a producer, to the rivalry between idols and production studios.
Informations Source: Wikipedia