Normally, you can tell how well a Vietnamese business is doing by the house above it. At the end of this alley is Bụi Sushi, in a five story house. I doubt, though, that selling sushi and sashimi alone yielded such a nice dwelling. I suspect someone in that household went to Japan. If back in Vietnam, he was familiar enough with Japanese cuisine to open this restaurant, and with his Japanese language skill, is working for a Japanese company. It's also possible this person in still in Japan and earning a salary there.