I can´t remember the title of this manga. It´s ahôjo and a one-shot, possibly by Shinjo Mayu (although there´s no rape involved). It´s about a girl whose only dream is to have sex once with her favorite idol singer. One day, she gets lucky, gets to meet him and sleeps with him (in a bar). Then she leaves, happy, having fulfilled her dream but the guy have fallen in love with her, looks for her, solves a misunderstanding and finally (how surprising!) everything ends well.
So? Do any of you know which manga I´m talking about?

The Poisonous Flower.

That was a fast one, thank you!