Viscountess Libitina (リビティナ 子爵 Ribitina-Shishaku?) is one of the main protagonists of the ALDNOAH.ZERO Gaiden: Twin Gemini side-story manga. She holds the title of Viscountess as a member of the Martian Knights. She pilots the Martian Kataphrakt Acidalia along with her twin sister Viscountess Libertina.