Overall sales of frozen food have stayed more or less flat, but one segment of the market -- namely ingredients packed into "bento" boxed lunches -- is showing robust growth.
Sales of such foods are being buoyed by retailers's efforts to broaden their product lineups and an increase in products and packaging that require minimal preparation before use, industry observers say.
Among frozen food products available in the past, most required additional cooking or deep-frying before they could be consumed.