日本歌謡大賞
Iwasaki made her official debut in April 1975 with the single "" — "Dyuetto", after winning a record contract on the popular Japanese talent competition show Star Tanjō! in the summer of 1974. The single peaked at no. 19, according to the Oricon charts. Its follow up, "Romance", peaked at no. 1, maintained its place for three weeks, and sold over a million units. It was written by Yu Aku and Kyohei Tsutsumi, and got her nominated for "The Best Newcomer of the Year" at the 17th edition of the Japan Record Awards, and made her first performance on the 26th edition of Kohaku Uta Gassen with this song. The disco inspired "Sentimental" was issued as a single in October of that same year, and with sales exceeding 700,000, became her second no. 1 hit, and maintained its place for two weeks. A string of hit singles was released throughout 1976 and 1977, most notably "Fantasy" (which peaked at no. 2), "Mirai" (no. 2), "Kiri No Meguri Ai" (no. 4), "Dream" (no. 4). and "Nettaigyo" (no. 4). The single "Shishūki" was released in late '77, and won her an award at the 19th edition of the Japan Record Awards, as well as an award at the 8th edition of the Japan Music Awards.