I think it was something like the Japanese ones were some of the really colorful ones, and that people would say, "non-indo" instead of "smuggled from Japan".
Later, people started calling other colorful stuff "non-indo" to capitalize on the whole Japanese cachet.
Just add it to the list of other terms you see thrown around... Rare, LE, True, Jap(anese).
Funny on Ebay etc, "rare" is the baseline, and it goes on up from there
