The song peaked at No. 2 on the Oricon weeklies and ended up being the 11th-ranking song of the year. It would become her biggest hit.
Saori Minami（南沙織）, who was born Akemi Uchima（内間明美） in Okinawa in 1954, was a huge fan of the lead singer of the most famous Group Sounds band in the 1960s, The Tigers' Kenji Sawada（沢田研二）, which got her to try out for show business. She and her parents went up to Tokyo and met with the president of CBS/Sony, who decided to take her on.
The origin of the song is a fascinating one. When Minami first met the composer Kyohei Tsutsumi（筒美京平） about her debut, he asked her about what she could sing. She responded that she could only do Lynn Anderson's "Rose Garden" which had been released several months earlier in late 1970. Anderson's country/pop crossover tune had been a huge hit worldwide, and so Tsutsumi crafted "Juu-nana Sai" with a similar sound for his young charge's sake. Go ahead....listen to the two songs. Mieko Arima（有馬三恵子）provided the lyrics.
Almost two decades later, pop singer Chisato Moritaka（森高千里） did a cover version with a Eurobeat feel. This was her 6th single and was included in her album, "Hijitsuryokuha Sengen"(非実力派宣言...Incompetent Faction Declaration) in 1989. It didn't do quite as well as the original but it still broke the Top 10 at No. 8 and was the 43rd-ranked song of the year.
Moritaka and Minami have something else in common besides this song. They both married celebrities with Moritaka marrying actor/singer Yosuke Eguchi (of "Tokyo Love Story" fame) and Minami wed photographer Kishin Shinoyama.