Tenshi Ja Nai!

From Go! Comi:
In the play of life, all Hikaru Takabayashi wanted was to be part of the scenery. Tormented by jealous schoolmates ever since she appeared in a famous commercial in grade-school, Hikaru transfers to a prestigious all-girls' academy where she hopes to settle down to a quiet life of anonymity. But when her new roommate turns out to be the super-popular TV idol Izumi Kido, Hikaru finds herself thrown smack in the spotlight's glare once more!

And as if living with a celebrity wasn’t bad enough, Hikaru discovers that there’s more to Izumi than her “good girl” image—she’s a he! And this is only the first of Izumi's many dangerous secrets! Now Hikaru’s the unwilling star player in a madcap tale of deception, abduction, humiliation and blackmail…you know—the usual romantic stuff.