The Making of Karateka, the new "interactive documentary" from Digital Eclipse on the classic martial arts computer game, is out right now. Karateka was released across multiple platforms, even NEC's PC-9800 series of personal computers in Japan. The Making of Karateka features some screenshots of the PC-98 version, but there's a whole playthrough of it on YouTube.
My experience with Karateka is mostly limited to the Famicom version, so I won't speak to any differences in gameplay, but the PC-98 version seems to run faster. The other major, and certainly the most obvious, difference is the music playing throughout the game, to the extent that they may have missed the point of the original game.
PC-98 Karateka was published by Brøderbund Japan and developed by a company called Masternet, an online service provider along the lines of CompuServe or AOL in the States. It was originally a subsidiary of Meiji Dairies Corporation. I know it's the same company because the same logo seen here also appears on a pamphlet for the online service seen here.
The ending credits are surprisingly lengthy. More people worked on this version of Karateka than any other, and yet I don't suspect Masternet had much to do with game development, at least outside of online games. I could not even begin to speculate on how they got involved with this.