Hi Rachelle.
It depends on your head unit, the stereo within the dashboard.
The below text assumes that you just have a screen in the rear and no ability to load in DVDs there etc.
Often the rear screen is just a repeater for what's on the front screen when the front is set to say DVD mode. The connection to that rear screen is done via the back of the stereo in the front. But, if your head unit is still Japanese you may find that you can't get UK or European DVDs to play on it anyway.
Can you send a photo and model number of the head unit?
We have a Vellfire ANH20 (2010 model) with a setup like this and are just about to replace the head unit so my research may well pay off for you too.
Tom