I haven't gone back to Japan for almost 3 years so I didn't know what kind of radars available in Japan.
When I was surfing the Internet, I found an interesting radar detector.
This is a RVM style, basically you just put on the existing mirror and connect it with either cigar socket or hard wire.
It has GPS so it will warn you if you are heading speed camera with real pic.
It looks good though, it has some drawbacks which is:
1) it shakes a little if it isn't fit
2) if you buy cheaper one, under $200 USD(the detector as shown cost around $300), it is difficult to see because of sunshine
3) I am not sure about the sensitivity of the radar. People say it works great though, I haven't even seen it with my own eyes.
If it can work in the US, I would like to buy one though, I need US map and data regarding location of speed camera and red right camera.
I am not sure if the types of radar used in Japan and in the US are same.
So I hope it would be released in the US officially.