US retail behemoth Wal-Mart looks set to raise its stake in beleaguered partner Seiyu of Japan. Wal-Mart has an option to raise its holding in the Japanese supermarket operator from 6.1% to 33.4%, and Reuters reports that the US giant is poised to exercise this option now that Seiyu has located a purchaser for its debt-ridden financing division, Tokyo City Finance (TCF).