I'm a (Fake) Saint Who Was Summoned to Another World, But Apparently I'm Fated to Die If I Don't Marry the Prince

Story :  "I'll return you to your world if you marry the prince." That was the shocking proposal of the self-proclaimed god! I won't really get a bad ending if I refuse, will I!? Office worker Sara was involved in a traffic accident, or so she thought. One moment, she was about to be hit by a truck, but that next... she found herself transported to an unfamiliar, grand castle, falling right on top of Prince Ars! When a soldier recognized her as "Sara," the saint who saved the kingdom five years earlier, everyone suddenly started treating her as some divine being!! After questioning her reality, a voice came to her and said, "Capture the heart of the prince, who longs for the saint, and marry him!" The voice then threatened her denying her return to her own world should she fail... Her only weapon in this challenge is her face that apparently looks just like that of the saint's! And so began her zealous attempt to steal the prince's heart!