there's three places where an import can be potentially wound back:
1. by the seller
2. by the export agent that sells the car
3. by the dealer who buys the car and keeps it on his yard in australia
and i've seen hard evidence of all 3. That said, being in the import game I made sure my cars weren't wound back (and since my odo reads 150,000kms atm, if they did wind it back, they didn't do a shit hot job of it). Buying from reputable dealers in japan, and presence of log books can help you make sure that the car is true to its k's. I tend to not trust a km reading on a car that has already been bought at auction by an export agent, usually they buy em cheap when they come up, touch em up (wind the k's back, light panel work, polish, clean) then sell em onto their buyers at a higher price. Much more safer to bid on cars at auctions that are coming up, so you can see all the detals of the car before the agent has a chance to tamper with it.