I have found this Mitsubishi metal halide lamp designed to retrofit mercury vapor lamps on Japanese 100W mercury vapor HX autotransformer ballasts if you would be interested:
https://www.jauce.com/auction/r1143926133Just as I mentioned earlier, it is only compatible with HX autotransformer ballasts and series choke ballasts.
Additionally, this website can help you get this lamp shipped to the USA.
Just so you know, 4800 JPY is about $31 USD. Additionally, I think with an item this small, the shipping costs might be reasonable.