Watashi no Tama-no-Koshi Keikaku!

Summary

In her previous life Erika used to be a beautiful princess living in luxury, but then she somehow reincarnated as a poor commoner. Hoping to return to that rich life, she applied to be a concubine at the royal place. She was tremendously happy to find out that she passed the examination, but little did she know that it was only the beginning of her troubles...