TENSHI JA NAI!! (I'm No Angel), by Takako Shigematsu. First published in 2003 and first published in North America in 2005.
Hikaru just wants to be left alone. She modeled briefly as a child and all she got out of it was a lot of attention from bullies. Ever since, Hikaru has done her best to coast through her school years without attracting any sort of attention. Her plans go to hell when her new all-girls' school decides to have her room with Izumi Kido, a popular actress and idol singer. Hikaru soon learns Izumi's secret: he's a man who only poses as a woman. Both Izumi and his manager Yasukuni are determined to keep this secret at any cost, and they are not above blackmailing Hikaru to achieve this. It seems that between this, jealous classmates, and some family secrets of her own, Hikaru is going to need to make some all-new plans if she's going to survive.
I really hate that I have to keep saying this, but it apparently needs saying again: Guys dressing like women is not funny, and blackmail is ESPECIALLY not funny. Just because this take on it doesn't involve making fun of a lesbian doesn't make it any better.
Hikaru is OK as far as heroines go. She's very loyal towards the few people who supported her during her bullying, but her experiences made her more than a little paranoid and learning the truth about Izumi only aggravates those tendencies. She's got a matter-of-fact tone that reminds me of Haruhi from Ouran High School Host Club. Sadly, she's the ONLY likeable character to be found within the entire volume. Everyone else either blends into the background or is actively hateful.
My biggest problem with Tenshi Ja Nai!! was this: why does Izumi have to present himself as a woman to succeed? It's not a matter of being trans or a transvestite as he doesn't seem to take any pleasure or comfort from doing so and never says anything to even suggest as much. There's no ostensible reason that he couldn't succeed as a male actor and idol singer. So why does he bother with the big charade? There is literally no reason he NEEDS to do this, and without that reason the plot just falls apart.
Even if he had a reason, he's still an irredeemable bastard who literally threatens to share naked pictures of Hikaru unless she plays along with his plans. Shigematsu at least tries to redeem the manager with a storyline about him rebelling against his rich family and having our leads come to his defense, but these attempts at sympathy are far too late and far too little to smooth over the fact that the plot operates on blackmail. That's a storytelling choice that you can't simply walk back without a lot of effort and Tenshi Ja Nai!! is not interested in making that effort.
The artwork here is nothing special. Shigematsu seems to prefer drawing very stiff, lanky, giraffe-necked, pointy, and heavily androgynous characters. They're not terribly good looking but it certainly works in Izumi's favor. Beyond that, everything else about her art is as boring and straightforward as shoujo manga can be.
Tenshi Ja Nai!! is no angel, but it's also not fun, not pretty, and not worth reading.
This series was published by Go!Comi. This series is complete in Japan with 8 volumes available. All 8 have been published and are currently out of print.