Yumiko Iwamoto is a Japanese voice actress currently affiliated with Mausu Promotion. She was born on June 15, 1970, in Aichi Prefecture. She initially worked under the stage name Yumiko Iwamoto before changing to her current name, Yumiko Yamaguchi. A graduate of the Katsuta Voice Academy, she joined Mausu Promotion, then known as Ezaki Productions, in 1998.

Her career in voice acting encompasses anime, foreign drama and film dubbing, video games, and narration. One of her early anime roles was providing the voice of Misako Takashina in the 2000 OVA series Sousei Seiki Devadasy, a role she also reprised for the subsequent video game adaptation.

Her television anime credits from this period include appearances in series such as Seikai no Senki, Meitantei Conan, and the OVA for Sousei Seiki Devadasy. In later years, her anime work has included roles in Heroic Age, Slayers Evolution-R, and the role of Tamako Takanashi in Papa no Iu Koto wo Kikinasai!.

Beyond anime, Iwamoto has built an extensive career in dubbing foreign films and television series. Her dubbing work includes providing voices for characters in projects such as ER, The X-Files, Star Trek: Voyager, and the Japanese television broadcast version of Die Hard with a Vengeance. She has also contributed to dubbing for films like Back to the Future Part III and the animated feature Shrek.

Her video game work includes roles in Tokyo Bus Guide, Sunrise Eiyuutan 2, and Tantei Jinguuji Saburou: Innocent Black. She has also worked in narration for commercial projects, including planetarium programs and corporate videos.