I heard this on one of the two Hiromi-chan cassette tapes that Mom got me when she and Dad came back from vacation in Japan in the mid-80s. It was a BEST compilation with all her songs dating up to 1984, and all of her earliest material just happened to wrap Side B. So I got to hear "Romance" and then "Sentimental" which is a bit more whimsical-sounding than the former song. Depending on my mood, I've often it liked it better than "Romance" .
Indeed, "Sentimental" was her second No. 1. And in the short time before the end of the year, it managed to become the 78th-ranked song on the annual charts which all the way up to No. 17 for the same charts for 1976. Of course, Iwasaki would continue to do well for the next several years, but her 3rd and final No. 1 up to now wouldn't come until 1982 when she had another megahit with "Madonna Tachi no Lullaby"（聖母たちのララバイ）.