A Greek retailer, The Console Club, has listed Dragon Quest Heroes 1 & II for pre-order for the Nintendo Switch. The game is available at a price of 60€, which is significantly less for an imported unit, thereby pretty much confirming the fact that this is not a Japanese unit.
This is the same retailer who had earlier leaked Assassin’s Creed IV Black Flag & Rogue. Considering the past records, this seems pretty credible.