Well it is a Sunday and Sundays used to be the night for "Enka no Hanamichi"（演歌の花道）on TV Tokyo way back when. However, considering some of the lovely sets of bars and nightclubs which appeared as settings for singers to ply their wares, I did wonder whether the show could have stood a title change to "Mood Kayo no Hanamichi". There was no way that I could ever find myself in one of those places without financial generosity (which was the only way that I was able to get into the few that I did get into) so Sunday nights were the time for me to live somewhat vicariously while listening to the music.
I don't know whether the Mood Kayo group Toshi Ito and Happy & Blue（敏いとうとハッピー&ブルー）ever managed to get onto "Enka no Hanamichi" in the show's glory days but I think their 4th single "Watashi Inottemasu" (I'm Praying For You) would be the perfect ticket. With that boozy sax and the nightclub piano, it's the ideal Mood Kayo to be set in an old-fashioned Ginza club.
Released in July 1974, it was composed and written by the late Hiroyuki Nakagawa（中川博之）under his pseudonym Satoru Igarashi（五十嵐悟）as a tearful but adamant lament from a female lover to her soon-to-be ex-paramour to get away from her and live a happy life (and don't drink too much). I mean, how Mood Kayo can you get? During those years when enka and Mood Kayo could regularly break into the Top 10 of Oricon, "Watashi Inottemasu" was a bit hit for Ito and Happy & Blue by not only peaking at No. 4 but also staying in the Top 20 for 15 straight weeks while selling a little over 440,000 records.
However, what I found out on the uploader's page and the footnotes for the J-Wiki article on Happy & Blue is that there was an original version of the song under the title "Shiawase ni Natte ne" (Be Happy). This was released in September 1970 after its recording by another Mood Kayo group called Naoki Matsudaira & Blue Roman（松平直樹とブルーロマン）. The video above uploaded by shego50s includes a recording of a rehearsal by the group at some nightclub. At this point, I don't know what the original recording sounds like but it was placed as a B-side although in April 1972, the song came out again as an A-side.
As for Matsudaira, he happened to be one of the members of Hiroshi Wada & Mahina Stars（和田弘とマヒナスターズ）before striking out on his own in 1970 with his own Mood Kayo group. He and Blue Roman broke up in 1983.
Apparently, the song is still performed on the kayo shows under its original title of "Shiawase ni Natte ne". For example, here is Yuuki Seguchi（瀬口侑希）, an enka singer who is a familiar face on those shows giving her cover of the song. Her version was also released as a single in January 2008.