According to the end credits (at the very end of this
video) of A Ressha de Ikou Z, there are two people credited for sound:
As usual in Artdink games, nobody is credited for music writing or composing, but in other games such as
this one, the person credited for lead/main sound is the only composer of the title. Bearing that in mind,
Masami Ozawa was surely the composer of A Ressha de Ikou Z and may have been assisted (or not) by Daisuke Nakakaze.
Anyway, this album also includes music from A-Train 3, 4, Evolution and 5.
The tracks from A-Train 3, 4 and Evolution included in this soundtrack as bonus tracks also appear on this
album (with composer credits).
The tracks from A-Train 5 were composed by Koshiro Nishida, as I already
explained.
See attachments for image verification of the end credits.