http://www.success-corp.co.jp/?page/category/2/
I know we have the Izuna / Izuna 2 soundtrack listed on VGMdb. However, there are about 10 others on this site, and I'm pretty sure they've gone unnoticed on vgmdb.
I don't know the games for many of them, but I did see there's a soundtrack listed for the game that Americans know as "Touch Detective."
Definitely worth looking into...