There are two versions of the game with completely different sound hardware from each other. One version, apparently only released in Japan, has FM synthesized music using a YM2610 (the same sound chip as earlier Psikyo games, not to mention NeoGeo) The other version, released worldwide as well as in Japan, has a wavetable synthesizer, the YMF278 (the chip used in Sengoku Blade and all later Psikyo games), and consequently much nicer sounding music. Psikyo would have had to rewrite the sound program and rescore all the music to use the more powerful chip--it's not a drop-in replacement (like buying a new sound card for your PC and having all your games sound nicer, back in the days when PC games used MIDI
)Did Psikyo decide to upgrade the audio for the worldwide release, and then subsequently release the improved version in Japan as well?