You could by running a 486 DX 4 100 or DX 2 80 with a VLB slot which has a pc-98 emulator running on it...but I think you are best off just buying a pc-98 in japan, make sure it has a standard power supply like an AT, then leave the powersupply and the case in Japan. Ship the rest of the stuff back in a STATIC proof way in a suitcase. This way you will only move a few pounds of hardware and will leave the real weight in Japan. Then go to a goodwill type store and get an AT case and hunt arount for a used AT powersupply (or whatever they use, I am assuming they use AT).
If you cannot find a PC-98 in a standard case, you are screwed.
Oh and if you try to go the emulation route, you might be SUPER lucky and might be able to find a P100-133 (no mmx) motherboard with a VLB slot and nothing blocking your ability to use the full length of the slot.
If you are not well versed in computer hardware, feel free to talk to me more about this.
Your best bet though is to strip down a pc-98 and transport the key parts back here though, then re-assemble it once you are home again.