I noticed on taking a look at the J-Wiki article on Shinichi Mori's（森進一）"Fuyu no Riviera" (Winter Riviera) where it identifies the genre, the song was labeled as enka but in brackets, the description in a somewhat rationalizing way that it was "pop music that an enka singer would sing".
And that was my exact initial response when I had first seen the veteran sing the song on an old VHS tape of an enka special many years ago. From that distinctive voice, it was indeed Mori but the song didn't sound like the usual enka ballad. At the time, I hadn't known about Eiichi Ohtaki （大滝詠一）but even then the music for "Fuyu no Riviera" struck me as being decidedly un-enka. It sounded very Western heroic which I have stated in some of my other articles for Ohtaki as being one of his characteristics when it came to his compositions. I was just able to catch the word "Riviera" as Mori sang it for safekeeping in my memory since I did enjoy listening to it. As for that title, I had assumed up until recently that it was referring directly to the famed resort area by the Mediterranean, but according to that J-Wiki article, Ohtaki and Takashi Matsumoto were looking to use it as the Italian word for "shores".
Matsumoto （松本隆）wrote the lyrics for the song that the late Ohtaki penned. It was released in November 1982 for Mori and became his first Oricon Top 10 hit in 9 years. And up to the present day, it would be his final Top 10 hit on the charts....it peaked at No. 10 where it stayed for 4 weeks and would become the 41st-ranked song for 1983. It would also win a Special Gold Prize at the Japan Record Awards and get Mori his 16th appearance on the Kohaku Utagassen to perform it. In 2012, he would appear for the 45th time to perform it again.
Once again, I'm going to refer to that J-Wiki article but when Ohtaki passed away suddenly late last year, Mori commented that "Even now, 'Fuyu no Riviera' is a treasured song for me. I will sing it with all my heart so that it reaches him."