She moved to
Funabashi,
Chiba Prefecture after her parents divorced when she was younger. She made her media debut in 1985 as a
gravure model in , a magazine for which her older sister was on the editorial committee. On 21 June 1985, she became the 19th member of Onyanko Club after auditioning on the TV program
Yūyake Nyan Nyan, and she appeared on the cover of their first album,
Kick Off. Shortly afterward, she and
Mamiko Takai, also a member of Onyanko Club, formed the group
Ushiroyubi Sasaregumi. She has been called by the nickname "Yūyu" since she was a little girl, and she was also called by that name on the program. From that point, she became the main vocalist for the majority of their albums, and was considered central to the success of the group. She made her solo debut with the single Angel Bodyguard(
天使のボディーガード, Tenshi no Bodīgādo) on 25 March 1987. In April of that same year, Ushiroyubi Sasaregumi was disbanded because Takai graduated from Onyanko Club and moved on to other things. It was said that she and Takai did not get along, which she subsequently admitted on a TV program. Iwai felt that Takai was privileged by
Yasushi Akimoto, a lyricist and broadcast writer at the time, which was also not amusing to her. The person she was closest to in Onyanko Club was
Minayo Watanabe, who was a year younger than her, and Iwai claimed that unlike the other members, she treated even the younger members as equals. Onyanko Club itself disbanded in August later that year, and Iwai began working for
Watanabe Productions (Nabe Pro) along with fellow Onyanko Club member
Sonoko Kawai. She also began working under her nickname "Yūyu", turning it into a stage name. Since then, she has appeared in variety shows such as and played an active role as an image character of the game software company
Taito. In 1994, she changed her stage name back to her real name "Yukiko Iwai", but by this time her activity was sluggish. At this time, she refused to hold a press conference with the media, saying she had nothing else to say. Then, she virtually retired from the entertainment industry. However, she had two children after her marriage. In 2002, she participated in the reunion event of Onyanko Club. Since then, however, she has not been seen in public. ==Discography==