The PC-9801 (also simply called PC-98) is a personal computer made by NEC, and the successor to the PC-88. It single-handedly allowed NEC to utterly dominate the Japanese computer market for almost 20 years (until the advent of IBM PC's), such that even the vastly superior in every way X68000 and FM Towns could not dethrone it. Reasons for it include a good head-start compared to it's rivals and a strong marketing campaign. There is this nice site dedicated to document the PC-98 games catalog. Go check it out.