SPOTLIGHT ~Senbou to Yokubou no Hazama~

Saori is cute, perky, and dreams of being a star! Along with the beautiful Yuna and the striking Erica, Saori is part of a new female pop group named Twinkle - and this hot little group is ready for their big debut!
But this tantalizing trio is about to discover that the music industry is ruthless and demanding of its female artists! First, band manager Masaki decides to give Yuna and Erica a special session in pleasure and pain... Then, as lead singer, it's up to Saori to get the band past Kijima, the shady don of the entertainment business. Using his position to fulfill his wildest desires with all of the hot new pop idols, he'll never even consider giving anyone a chance at a big break until after his carnal desires have been satisfied. Saori's mother knows this all too well; to get Twinkle noticed, she's already given in to his erotic demands.

[From AniDB]