Yumeko Sakurai is an idol and the rival of Akizuki Ryo's who chases after her dream no matter what it takes. She appears in Idolmaster Dearly Stars.
She is described as an extremely talented idol until it was revealed that she cheated her way to the top, giving other idols candy that clogs the vocal chords or sabotaging the stage so the other contestants screw up.
Yumeko is also considered a tsundere type character, even though as rivals she hangs out with Ryou frequently to talk about their upcoming auditions.