Read manga: Otome No Iroha!

manga
Summary:

Iroha, a masculine girl, and Hifumi, a feminine boy, are siblings who have transferred to a different middle school and moved to their grandparents’ house. However, after the first night much to their surprise they both change bodies, Iroha into a boy and Hifumi into a girl while Iroha tries to get back her girl body how will this turn?