Seven-Eleven Japan Co., the nation's biggest convenience store chain, and three other companies on Tuesday announced plans for a joint venture in the nursing-support business, a lucrative sector amid the country's rapidly aging population.

The move may help cement Seven-Eleven's dominance in the retail market as it takes advantage of its convenience store network, which provides a strong infrastructure for online services.

The other partners in the new joint venture, capitalized at 300 million yen, are trading house Mitsui & Co., electronics firm NEC Corp. and Nichii Gakkan Co., a top domestic provider of hospital management services.