A few hours ago, I received an e-mail via the Contact Form regarding the late aidoru Yukiko Okada（岡田有希子）who had committed suicide back on this day in 1986. The person was inquiring about the "Star Tanjo"（スター誕生!...A Star Is Born!）audition program on NTV in which Okada, under her real name of Kayo Sato（佐藤佳代）, entered the singing contest on the show. The question was that although Sato had sung Akina Nakamori's（中森明菜）"Slow Motion"（スローモーション）at the national level at the March 30 1983 competition, the inquirer wanted to know the other song she had performed in the preliminaries to get to the nationals.
Well, it was a lucky thing that I got the question on a day in which 1) I wasn't off to see my anime buddy and 2) there were no translation tasks miring me down, so I was quite free to do some investigative work. Doing a bit of digging into the J-Wiki article for Okada through her quite voluminous history, I was able to find out that the Aichi Prefecture-raised teenager had skipped school to try out for the the Nagoya preliminaries of the contest. The song she sang was "My Boyfriend" by aidoru/actress Sawako Kitahara（北原佐和子）which you can see from 0:22 of the above video.
For some reason, the footage above states that this was an October 1983 broadcast so I'm not sure whether there was some long delay between the actual taping and the broadcast (doubtful) or whether the October show was some sort of retrospective showing past auditions. In any case, Okada had done well enough to receive her invitation to the nationals albeit not without some major conflict with her family and homeroom teacher, according to the book "Yukiko Okada ~ Ai wo Kudasai"（岡田有希子 愛をください...Yukiko Okada - Love Please）via that J-Wiki article.
As for Sawako Kitahara, she was born in Saitama Prefecture in 1964 and made her debut as an actress and as an aidoru around 1982. Just before that, she had been in a 1981 aidoru group called Pansy（パンジー）before going solo. "My Boyfriend" was her debut single from March 1982 with lyrics by Mari Horikawa（堀川マリ）and music by Tatsushi Umegaki（梅垣達志）. From that year to 1986, Kitahara would release 10 singles and 6 original albums.
Although she has long finished her singing career, her acting career has been continuing and she is also a certified care worker. In any case, I hope this article has answered that one question.