I have never seen this system so I could be very wrong, but I doubt the tuner is in there.
Posts on various auction sites suggest the tuner is actually in the the outboard trunk mounted unit.
Here are a couple of not so great pics of the complete package found on auctions sites:
My guess is that it is an NTSC system that tunes the Japanese TV and FM bands.
Similar elaborate systems find there way here every now and then when people import used luxury cars from Japan. The new owners rip them out to install something with more amplifiers and subwoofers.
I once bid on a very elaborate Pioneer system at a local (not online) auction. It consisted of a double DIN head unit (LCD display in this one), seperate TV tuner/AV switcher, 12 disc CD changer, sat nav unit (which had a CD changer in it for map cds), GPS receiver and power amps. Five seperate units and lots of cabling with weird custom connectors. I didn't get it, I could only justify so much for something which while cool to play with would be completely useless in the country. I doubt they buyer that did get it realised this.