Time Travel Girl (タイムトラベル少女～マリ・ワカと8人の科学者たち～ Time Travel Shoujo: Mari Waka to 8-nin no Kagakusha-tachi, lit. “Time Travel Girl: Mari, Waka, and the Eight Scientists”) is an anime television series directed by Osamu Yamasaki. Cast members of the series include all four members of the seiyuu unit Sphere.
Time Travel Shoujo is based on a 1983 book titled Jishaku to Denki no Hatsumei Hakken Monogatari by Japanese educator Kiyonobu Itakura. It is part of the Hatsumei Hakken Monogatari Zenshuu series which describes the story of various scientific discoveries and inventions throughout history. The 1983 book focuses on discoveries related to magnetism and electricity.