When I was translating those travel articles, some of those included those for river tours out in the regional areas of Japan with the traditional boatmen steering their wooden boats skillfully through the rougher patches of the waterways.
It was those scenes that came to mind when I heard the enka ballad "Koi no Sendo-san" (Boatman in Love). This was actually sung by the enka legend known for decades as Hiroshi Itsuki（五木ひろし）but his 3rd single from August 1965 was released under his first stage name Masaru Matsuyama（松山まさる）.
Written by Toshio Oka（丘灯至夫）and composed by Gento Uehara（上原げんと）, the delivery by the singer who would later be known as Itsuki has that youthful smoothness for the lack of a better expression, but the lad was only 17 years old at the time. Still, considering that he was still three years away from being officially recognized as an adult in Japan, his voice is still remarkably rich and steady as if it were from a singer a decade older.
The lyrics by Oka relate the story of a young boatman, having taken on the duties formerly performed by his father, falling for a beautiful passenger who takes a ride under his charge. He then spots her at a festival and falls for her head-over-heels. There's no report on whether the song inspired any movie but the setting sounds like a perfect source for a screenplay. I also don't know how the song did in terms of sales but of course, the best was yet to come for the man who was born Kazuo Matsuyama（松山数夫）.