I noted this fact in another release here on Archive.org called "Bonus Levels" - The western world loved videogames back in the day, but music relating to games often wasn't heard at all other than when you were playing them.

In Japan, however, it was perfectly normal for professionally recorded songs to be contracted by gaming companies, and for the voice actors (that provided even the smallest clips for fighting games) to record singles and full-on albums in-character.