Eiko Masuyama is a veteran seiyū who works for Aoni Production. Her real name is Tomoko Masada.

She is most known for the roles of Fujiko Mine (Lupin III), Kisaragi Honey (Cutey Honey), and Bakabon's Mama (Tensai Bakabon).

Ironically, she was the voice of Mine Fujiko in the original 15-minute pilot film used to sell the series to Yomuiri TV. However, in the first TV series, she was replaced by Nikaiido Yuuko.