The game you linked looks like Princess Maker 2. I'm not sure where Idol Project came from. Also, it looks like you can just mount these floppies in Neko Project and it runs without any additional setup (disk A in FDD1 and disk B in FDD2 to start). Is there even an option to install this game on the PC98 from inside the game? I assume not, so you'd want to just be swapping the floppies when prompted. There is no simple way of just installing games that were meant to be run off the floppies to the hard drive. It requires modifying config files and basically knowing exactly what you are doing, and even then there is no guarantee it will work. I've been using DOS systems since I was 5 and I doubt I'd be able to figure out how to get most games to run off the hard drive, so you'll probably have to end up switching floppies like regular PC98 users used to. Also, this game is in Japanese so I hope you know that well enough to enjoy this. Looking at Wikipedia, this game also had some sort of English release (IBM-PC DOS I think) if that is what you're looking for.