Shortly afterward, she and Mamiko Takai, also a member of Onyanko Club, formed the group Ushiroyubi Sasaregumi.

[2] Yukiko Iwai performed the lead vocals for Onyanko Club's fifth single, Osaki ni Shitsurei, released in July 1986.

[13] 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.

[14][15] In April of that same year, Ushiroyubi Sasaregumi was disbanded because Takai graduated from Onyanko Club and moved on to other things.

[17][18] Iwai felt that Takai was privileged by Yasushi Akimoto, a lyricist and broadcast writer at the time, which was also not amusing to her.

Age Difference Doesn't Matter (クイズ!年の差なんて) and played an active role as an image character of the game software company Taito.