It starts with Christmas tunes in the background as a taxi pulls up to a railroad station - goes to the sound of high heels walking then running for the train, whistle blowing, the locomotive chugging to life.... The music is at first soothing strings, but gradually it shifts into a jazz swing with clarinet. Seiko finally starts singing just after the 3 minute mark. The music takes on a Latin rhythm turning into a tango. Amazingly complex for a "pop" tune. The voices in the intro, including railroad announcements, are in English, the song itself, other than "please don't go", in Japanese.
I hope you enjoy it. Happy holidays.