Eriko Ishihara was a Japanese voice actress born on May 16, 1983, in Kanagawa Prefecture. She was active in the industry for a brief period from her debut in 2002 until 2004, during which she was affiliated with the talent agency 81 Produce.

Ishihara made her professional debut in 2002, with early roles in children's anime series such as Mirumo de Pon! and Tottoko Hamtarou. Her career progressed, and in 2004 she was cast in leading roles that marked her as a promising up-and-coming talent. That year, she voiced the character Yukari Sagisawa in the visual novel Memories Off: Sorekara and its anime adaptation, Memories Off 3.5. She also played Atsuko Akanegi, one of the main heroines in the television anime series Diamond Daydreams, an adaptation of the Kita e visual novel. Her other voice roles during this time included a minor part in the series Elfen Lied.

Ishihara's career came to an abrupt end in late 2004. It was revealed that she had been working as an adult video model under the pseudonym Usada Hikaru, appearing in several productions for the studio Moodyz. Following an investigation by her agency and subsequent media reports, Ishihara admitted to the work. As a result, 81 Produce terminated her contract in October 2004, and her agreement with Moodyz was also cancelled. This effectively ended her career in both voice acting and adult entertainment. Following her dismissal, she filed for personal bankruptcy. After this incident, her public activities ceased and her subsequent whereabouts became unknown.