Koukyuu mo Nidome nara: Shiro Butahi Sairaiden

Jurei, a royal concubine nicknamed "Snow White Sow," was banished to the red-light district after being falsely accused of a crime. Four years pass, and she’s kidnapped and makes a return to the harem. Getting recognized will only spell out death for her! But because of her slimmed down figure and the newfound shining determination in her eyes, she gives off the air of a completely different, astounding beauty! Her attempts at escaping backfire, and the skills she developed in the red-light district prove so useful that she ends up becoming a consort candidate to the emperor. Can Jurei escape the harem without anyone discovering her true identity?!

(Source: Manga UP!)