Shiho Niiyama was a Japanese voice actress born on March 21, 1970, in Ehime Prefecture and raised in Nara Prefecture. She was a graduate of Osaka University of Foreign Studies, where she majored in Danish, and her involvement in theater clubs during her school years led her to pursue a career in voice acting. In 1990, during her third year of university, she enrolled in the Aoni Juku training school in Osaka. Upon graduating from university in 1992, she officially joined the talent management firm Aoni Production, starting her professional career alongside notable contemporaries such as Megumi Ogata and Rumiko Kasahara.

Niiyama's voice acting career, though brief, was marked by a wide range of roles across television anime, OVAs, and video games. Her early work included the television anime series Marmalade Boy, where she voiced Doris, and the OVA Battle Skipper, in which she played the role of Rie Shibusawa. She was also the voice of Gina Daggats in the series Shinken Densetsu Tight Road and Kimiko Ayanokouji in Debutante Detective Corps. A notable recurring role was Momiji Kagariya in both the Starship Girl Yamamoto Yohko and Starship Girl Yamamoto Yohko II OVA series. Her filmography also includes the film Spring and Chaos, where she voiced the character Taichi.

Beyond the roles specified in the query, Niiyama was well-regarded for several other prominent performances. She is widely known for her role as Seiya Kou / Sailor Star Fighter in the popular anime series Sailor Moon Sailor Stars. In this role, she demonstrated her vocal range by portraying the character in both his male and female forms. Other significant roles included Suou Takamura in CLAMP School Detectives, Risa Kanzaki in Neighborhood Story, and Deedlit in Record of Lodoss War: Chronicles of the Heroic Knight. Her work extended to video games as well, such as voicing Roxanne in Eternal Melody and Bakuryu in Bloody Roar 2.

In addition to her acting, Niiyama was also a singer. She performed theme songs for series like Battle Skipper and Debutante Detective Corps, and sang insert songs for Sailor Moon Sailor Stars. She was part of a voice actor singing group called Virgo, formed with the cast of the anime and game Ojōsama Sōsamō, and released a CD single with the group in 1996. Her other talents included playing the piano and violin, and she was also a radio personality, hosting the program Run! Kayōkyoku on Bunka Hōsō.

In the summer of 1998, Shiho Niiyama was diagnosed with acute leukemia and subsequently withdrew from work for treatment. She underwent a bone marrow transplant and showed signs of recovery by the end of 1999. However, she passed away on February 7, 2000, at the age of 29, due to complications from pneumonia and internal bleeding. Her final role was as Deedlit in the television series Record of Lodoss War: Chronicles of the Heroic Knight. Following her death, several of her ongoing roles were taken over by other voice actresses, including Junko Noda and Makiko Ōmoto.