Koizora (Sky of Love) (2007)

In this intimate story of teenage love, a high-school girl named Mika finds her life changed forever when she loses her cell phone. After retrieving it, she begins receiving calls from a secret admirer and after a summer of getting to know each other over the phone, they meet. The boy turns out to be a young man named Hiro, and the two find that their chemistry is just as potent in person. Their relationship turns serious as well as physical, but Mika's jealous ex-boyfriend throws a horrifying wrench into her happy new life when he hires a gang of thugs to rape her. Traumatized and confused, Mika turns to Hiro to find that their bond together has only grown stronger, but things don't remain calm for long, as Mika soon discovers that she's pregnant. Faced with yet another challenge to their youthful love, she and Hiro face their future together.