"Wakakihi Bourou" (Watchtower of Youth) is a Taeko Ohnuki（大貫妙子） creation that was included in her 4th album, "Romantique" from 1980. As I mentioned for the article on that album, it was a special release in that this was the LP that showed a new Ohnuki approach. She started creating her own technopop (thanks to her YMO buddies) and more languid European melodies, away from her former New Music stylings.
This particular song from the album is more on the French side of things as Ohnuki sings about the protagonist looking back at the old days of youth that will never return. According to J-Wiki, Ohnuki didn't write the song as a rose or sepia tinted trip to nostalgia; in the lyrics, she also mentions about the hard times when money was not in great supply, although I think the overall tone of the song is rather bittersweet instead of contented/satisfied. The image seems to be one of looking at that faded photo album in the retirement home.
Ryuichi Sakamoto（坂本龍一） arranged "Wakakihi Bourou", and I thought the instrumentation bookending the song was pretty interesting. The intro has that introspective classical piano and the end has that "lonesome cowboy" twangy guitar which hinted to me that The Professor wasn't completely obsessed with computer music at the time.
But the first time I ever heard of this song was actually through her self-cover in which Ohnuki sings it totally in French under the title, "Amour Levant". The song was included in that double-CD BEST album that I got of hers, but it was originally part of her 8th album, "Kaie"（カイエ） which came out in 1984. The arrangement though here is more dream-like and orchestral.