A very unusual plant indeed. I did a web search on this one and got 8 hits. Not 8 million, just 8. We got it from Asiatica Nursery, now closed, so I can't even tell you where you might get one of your own.
Oddly enough, this is the only Dutchman's Pipe that we grow. I've always been fascinated by the odd flowers, but just never got around to having one. It's a little harder to find places for vines since they need something to climb on, so I just put off buying one for my garden. When I saw the picture of this one I decided I would find a place for it, being a bit of a push-over when it comes to variegated plants, especially unusual and rare ones. It grows in light shade or just morning sun and is happy in zones 6-9.
Not only is this variegated form rare, the species itself seems to have very little information available (except in Japanese). I did find that it is from a small area in southern Japan in the mountains It is named after a botanist, Ono job, from the early Meiji era. I have only found one caterpillar/butterfly that uses it for food, and since that one lives in the native range in Japan, I don't expect anything to bother it (and in 2 years, nothing has so far). It seems to be rather slow growing, last year barely growing any (probably just growing roots) and this year is now about 6 feet long. I'll take photos, for sure, once it blooms.