Apparently, during the last decades of the last century, lots of Japanese—and lots of Japanese money—moved into the islands. (The smart-ass who'd written the article I read said something like, "After the Japanese couldn't conquer Hawai'i in World War II, they came in afterward and bought it.") Add a large resident Nihonese population to the influx of tourists from Japan-based megacorps, and that would explain it.