I don't know Mieko Hirota（弘田三枝子）all too well outside of her rare appearances on TV nowadays and her trademark song "Ningyo no Ie"（人形の家）, but I did encounter this ballad she released a number of years after that hit.
Titled "Cho no Ame" (Butterfly in the Rain), I saw a YouTube comment comparing it to an Italian canzone in terms of its passion and delivery. And I had also thought that Hirota had been providing a Japanese-language cover of a song originally performed in Italy or France. However, as it turned out, this was a Japanese creation all the way. Lyricist Rei Nakanishi（なかにし礼）and composer Koji Makaino（馬飼野康二）were responsible for this ardent love song about the depths of a woman's love being compared to a butterfly withstanding all that rain.
Apparently, this April 1974 single didn't score too highly on Oricon which is a pity. However, being counter-intuitive here, perhaps in a way it is good for me since this has turned out to be a pleasant discovery that hasn't gotten too much exposure...kinda like my own little treasure. Makaino also arranged "Cho no Ame" which starts out softly with piano and Hirota's soft voice before things get more epic with her vocals soaring high and a boss brass section punching itself in.