Sumi Mutoh is a Japanese actress and voice actress born on May 18, 1971, in Tokyo. She has been active in the entertainment industry since the 1990s, building a career that spans both live-action film and animated voice work.

Mutoh's body of voice acting work includes several notable roles in animated films and television series. She provided the voice for Kei Amemiya in the 1999 animated film Jin-Roh: The Wolf Brigade. In 2002, she voiced the protagonist Mikako Nagamine in the acclaimed science fiction anime Voices of a Distant Star. Her television roles include Mayumi Morishita in Shiawase Sou no Okojo-san, Chisa Yomoda in Serial Experiments Lain, and the Zashiki-warashi in xxxHOLiC. She also had a role in the 2004 film Ghost in the Shell 2: Innocence.

Her work has led to collaborations with prominent directors in the animation industry. She worked with director Makoto Shinkai on Voices of a Distant Star and with director Mamoru Oshii on Ghost in the Shell 2: Innocence. Her marriage to animation director Kei Oshii, who directed Jin-Roh: The Wolf Brigade, is another point of connection to the industry.