in the USA you can track with a cheap cellphone , but I am not sure if thats available in Japan ,

I would think that since Japan is a dog lover country that there is something to track lost dogs,
They even sold a lost kids GPS at BestBuy !

Big problem is that these things have batteries that will need to be changed / charged..

If you were in the USA this would be easy , but even at its best GPS is still only going to get you close ,

RB