Suburban restaurants, which constitute 85 percent of the company’s approximately 640 outlets nationwide, served sushi on 120-yen ($0.86) yellow plates, 180-yen red plates and 360-yen black plates.

Japan’s conveyor belt sushi restaurants (or kaitzenzushi restaurants, as they’re called in Japanese) are at a bit of an identity crossroads. Making up a whole bunch of plates of sushi ahead of time ...