TOKYO — Walt Disney Japan and Yahoo Monday revealed plans to strengthen their co-operation in the Internet biz.Yahoo will start running the Disney games site banner on its Yahoo Games and Yahoo Kids sites beginning Tuesday. Also, Disney will link to the Yahoo sites on its games site, Disney Games. The object is to join the contents of Disney and Yahoo Japan, enabling users to play the games more easily. The two companies will also co-operate in ad placements on each other’s sites. Disney and Yahoo are already collaborating on mobile service, Disney Mobile, that Disney launched on March 1 with the support of SoftBank Mobile Corp. The new deal expands the target of that partnership to PC users.