When I first read the title for this Tonosama Kings（殿さまキングス）hit, "Meoto Kagami" (A Mirror for a Couple), I wondered what it meant because I have had the feeling that the mirror has found itself in a number of kayo titles. So I did some digging. I remember from my university education that the Imperial Regalia of Japan included the mirror Yata no Kagami（八咫鏡）which may be enshrined in Ise Grand Shrine in Mie Prefecture. Supposedly, the Yata no Kagami could represent "wisdom" or "honesty".
So, perhaps that's where the significance of "Meoto Kagami" might come into play. Maybe it talks about the honesty between a couple...or the lack thereof. This enka ballad was the 5th single by the Tonosama Kings released in May 1974, and it followed up the group's megahit of "Namida no Misao"（なみだの操）from the previous year.
The karaoke video above, which also has the Kings singing the lyrics, shows the situation of a wife who is carrying out her last duties before leaving her husband for the last time. Perhaps she may have found out that the heel was philandering or he was simply paying more attention to his career than to her. The strange thing is that according to Kazuya Senke's（千家和也）lyrics, the wife seems to be intimating that it's all her fault for the breakup and that she no longer wants to be a burden on him.
Masao Saiki（彩木雅夫）was responsible for the unexpectedly jaunty melody, and both him and Senke were behind "Namida no Misao", most probably in the hopes that lightning would strike twice for Tonosama Kings. There was no need to worry. Although "Meoto Kagami" didn't become the No. 1 single of the year like its predecessor, it was still a No. 1 on the Oricon weeklies for almost a straight month and sold 1.5 million records. It ended up as the No. 6 single for 1974.
I didn't mention this in the article for "Namida no Misao", but Tonosama Kings struck me as this rather interesting quartet that had that look and sound of a typical Mood Kayo group but actually sang enka tunes. Mind you, the way they sang both "Namida no Misao" and "Meoto Kagami" could have had them straddle the line between the two kayo genres.