Chi wo Hau Boukoku no Oujo
Evita lived happily as the princess of a small kingdom, until it was invaded and taken over by a neighboring country, and her family was cruelly killed. Evita survived, but she was sold to a brothel and forced into prostitution. Then a man from the royal family, the one she hates so much, appears as a customer...
(Source: Gangan Online, translated)