Boku wa Ohimesama ni Narenai

is a Japanese manga series written and illustrated by Toshiya Wakabayashi. The manga was serialized in Dengeki Daiouji and published in Japan by ASCII Media Works under the Dengeki Comics NEXT imprint from September 2014.

Synopsis
From the master of love comedy manga, Wakabayashi Toshiya, comes a high school fairy tale about love☆!

Shindou Rei (Cinderella) comes from a very poor family. Her only clothes are hand-me-downs from her brother, even her school uniform. So everyone always mistakes her for a boy. Even her close friend Hakuba Ouji (white horse prince), who starts developing confusing feelings toward her all the while believing she's a boy. Tsukumo Yuki (Snow White) is the leader of a delinquent gang and falls in love with Rei at first sight, also believing her to be a boy.

(Source: Manga Updates)