The HVR series is part of Sony's "professional" line. You won't see HVR parts in the consumer area. It does not matter if it is "J"apan-localized. That is pretty much related to the frame rate options and language displayed in the menu. The HVR-A1 is still available from Sony - the XLR adapter was sold with the camcorder and not as a separate "add-on". That's why - at the Sony pro website (US) - the XLR adapter has no separate part number
and click on the "accessories" tab.
I *think* Sony lists it in the pro area as "XLR BLOCK ASSY" under part A1133621A (or A-1133-621-A). I was looking to add it to my HDR-HC1, but decided against it (because it requires removal of the built-in flash the HC1 has that the A1 does not have).
The HVR series camcorders are not sold through regular retail outlets, but "authorized dealers". So you can either find an authorized dealer willing to sell this XLR adapter to you or just use an XLR adapter from juicedLink or BeachTek. I use both with my Sony HDRHC1 (the "consumer" sibling to the HVR-A1) all the time. And actually, I like them better - they lower the camcorder's center of gravity which allows for better control. The stock XLR adapter from Sony makes the HVR-A1 too top-heavy.
The HVR-A1 is not discontinued.