TOKYO -- Japan's humble conveyor-belt sushi industry ran into controversy this month after the arrest of a top executive, adding to the pressure on the low-price businesses caused by rising inflation and the weak yen.

The then-president of Kappa Sushi, Japan's fourth largest operator with about 300 stores, was arrested by Tokyo police on suspicion of illegally obtaining operational data from a competitor, Hama Sushi, where he previously worked.