Seven & I Holdings Co., operator of Seven-Eleven Japan Co., formally announced Monday it will acquire department store giant Millennium Retailing Inc. for about 130 billion yen, creating the country's largest retail group.

The announcement of the June merger in the waning days of 2005 marked yet another tectonic shift in the Japanese retailing landscape.

Earlier this month, Seiyu Ltd. officially became the Japanese unit of Wal-Mart Stores Inc. of the U.S.