Haruko Momoi(桃井 はるこ,Momoi Haruko?, born December 14, 1977) is a Japanese voice actress and singer/songwriter. She also produces an all-female pop group called Afilia Saga. She was born in Tokyo, Japan and is affectionately referred to as 'Halko' by her fans, a nickname she gave herself which is inspired by HAL 9000, the onboard computer of the Discovery in the movie 2001: A Space Odyssey.
During the late nineties, Haruko began singing and doing live performances on the streets of Harajuku and Akihabara. She then debuted her single "Mail Me," a cover version of which appears in the movie Suicide Circle in 2000. Soon after, she debuted as a voice actress for her role as Komugi Nakahara in Nurse Witch Komugi. In 2002, she paired with Masaya Koike to form the duo UNDER17 and together performed songs for adult and mainstream video games and anime. After their last album Best Album 3 ~Soshite Densetsu e...~ and a live tour of the same name, UNDER17 separated in 2004 citing creative differences, and the two musicians have since gone their separate ways. She continued on with her solo singing career and in 2006, was signed under avex mode as a music composer and singer.
In 2007, Halko published an autobiography entitled Akihaba-LOVE, in which she tells of the major experiences that shaped her life, mainly those that were important in constructing her career as a musician and voice actress, but it also includes anecdotes from her childhood and stories of friendship, as well as personal opinions on different aspects of anime fandom.