Only place I could think of is Yahoo Japan Auctions. They seem to have everything there, but unless you have a middleman who can order and ship you the stuff, and you pay them (oh the import fees can be killer though), it can be a bitch as no one outside Japan without assistance can order.
Also didn't that come out for MSX instead of PC? The very first Lolo title that the NES didn't get, and the first one overall. Or was it a later title that came out on an obscure Japanese computer, ala Sharp X1, NEC PC 8801, or 9801?