Why don dorama soundtracks carry the theme song?
Remember that in Japan, CD singles are more important than albums. Therefore, they want you to buy the CD singles for the theme songs. The albums will carry the theme music. Sometimes though, music with vocals are on super popular dorama soundtracks like “Long Vacation” and “Love Generation” but not the main theme song but the other songs with vocals. If you hear that somebody does have a soundtrack with the theme song, more than likely it’s from somewhere in Asia (Taiwan, Hong Kong).
