When I was scoping out the information for this song a while ago, I figured right off the bat that the title was referring to some sort of flower or plant according to that final kanji「草」. It took me a bit but I realized that nirinsou is the Japanese name for a certain type of wind flower called anemone flaccida, which could be the flower being referred to above.
Getting to the nitty-gritty, though, I heard "Nirinsou" on a previous episode of "Uta Kon"（うたコン）, and since I haven't put down any Miyuki Kawanaka（川中美幸）article since her first one, "Futari Zake"（ふたり酒）, all the way back in 2013, I thought it was time to amend that oversight (although Noelle was able to put "Shucho Monogatari"（出張物語）up for the veteran enka singer in 2015).
With all of the pop music coming onto "Uta Kon" nowadays, it's always pleasant for me to hear some of the traditional kayo again. And for some reason, there is something especially sweet and homey about hearing her 45th single "Nirinsou" which was originally released on New Year's Day in 1998. Perhaps it's the strong and delicate arrangement of the tune along with Kawanaka's delivery of the story about the enduring life of any married couple. I'd been wondering what the connection was between Kaoru Mizuki's（水木かおる）lyrics and anemone flaccida...it turns out that the wind flower has its blossoms paired up. Tetsuya Gen（弦哲也）was responsible for the melody.
"Nirinsou" didn't crack the Top 10 but it made it up a respectable No. 16 on Oricon and ended up as the 92nd-ranked single of 1998 and even hung around for another year to finish at No. 133! It went Platinum (becoming a million-seller) and won for Best Song and Best Arrangement at the Japan Record Awards in 1998. Kawanaka even sang it a total of five times at the 1998, 2005, 2008, 2010 and 2011 broadcasts of the Kohaku Utagassen.