Jazz and I are pretty good friends, especially smooth jazz with an introspective mood. "Sky Restaurant" fits perfectly into that category and even sounds somewhat melancholic. Perfect choice of images on the Youtube slideshow above (that video was taken down...replacement above). It's the kind of number you'd play at dusk while overlooking the city from the top of a high-rise building. The opening lines "Pa pa-pa pa-pa-pa" hit me pretty hard before a single word was uttered. Now, my Japanese isn't exactly that great at the moment but from what I understand of the lyrics, the topic here is lovers' separation. Yuming was the one who supplied those, and according to J-Wiki, they were originally tentative lyrics for her own single "Ano Hi ni Kaeritai". Perhaps someone with a better Japanese ability can enlighten me on what's going on here. As for music, the composition credits go to Kunihiko Murai (村井邦彦). The single was released on November 5, 1975.
The version that I have on my CD is actually a live recording from 1989. The new arrangement gives it a bit of a bossa nova touch and features a nice trumpet during interludes.