"Kotoshi no Fuyu" (This Winter) is another one of those tracks I found on one of my J-Xmas compilation discs. It is a heartwarming if somewhat sad song written and composed by Noriyuki Makihara（槇原敏之） about a couple having to be apart for some period of time. The song was actually released in early January 2003 as Akita-born singer Eiko Matsumoto's（松本英子） 7th single, but I guess with the theme of loneliness at an important time being a popular one where J-Xmas tunes are concerned, "Kotoshi no Fuyu" must have made an ideal tune for Tokyo.
The version I have on the CD has Matsumoto featuring Makihara, but the video above just has the former. I've only actually heard Matsumoto for this song, so if anyone can recommend any other songs by her, I'm all ears. As it is, though, she has a lovely voice reflecting that melancholy. The song went as high as No. 48 on Oricon.
Makihara also did his own more orchestral cover of the song.