Japanese mirror
 

Now then , how to source a Japanese migrant when you need one !

Or learn fluent Japanese !

This works https://www.onlinedoctranslator.com the translated doc was too big to upload so you'll need to do it yourself. Click the 'Translate Now' button and upload.

Not much changed since your last try then....
https://www.scoobynet.com/scoobynet-...ew-mirror.html

Have you tried YouTube? I can't think of many things there aren't 'how to' videos for on there, we use it all the time.

Japan doesn't have its own separate system of GPS satellites, it uses the same global GPS system as the rest of the world.
If the seller actually meant that it uses a Japan-only database of radar locations (in other words, speed camera sites!), which is loaded via the SD card, then that makes perfect sense, and I would struggle to believe that a compatible UK replacement card in the right format would be available.

Make it worth my while and I can easily enough split the pdf and get both halves translated. I think you'd be wasting your time though, as your gizmo is designed to do something it's never going to be able to do outside of Japan (warn you of speed-camera sites in Japan).

As above, GPS is the Global Positioning System, which is a recognised acronym globally and as its particularly referenced in the manual likely means its using that not anything "local".

The Japanese speed camera database will be being held on the microSD card. Take the card out, put in a card reader and edit the POI or .gpx file to see the format. There is a good chance it is compatible with the POI system that is used in the UK. If not, it should be possible to download the UK version from https://www.poibase.com/en/ and change it over to the mirror's version using excel or similar. It may just be a straight switch/copy over if you're lucky.

The mirror will read the POI database and when it sees it is near a speed camera, will display the necessary alerts (although probably still in Japanese!)