Kiyotaka Sato, Shintaro Hirakawa, and
Shun-ichi Hanawa are credited for "sound":
The names aren't the easiest to make out, but all three previously worked together on
Heartbeat Scramble. All three are apparently VGM composers, but the credits don't specify that they all composed for the game. Hirakawa's works list says he was responsible for all arrangement/sound conversion and sound effects, so I think in all probability that leaves co-composition for the other two, but maybe one of them was just a sound producer or director or something.