TOKYO (Reuters) - Japan and the United States are preparing to hold a summit meeting around May 25, government sources told Reuters on Friday. Prime Minister Shinzo Abe and President Barack Obama will likely meet ahead of a Group of Seven summit to be held in western Japan on May 26 and 27, the sources said, declining to be identified because the schedule is not yet official. They are expected to discuss issues such as the global economy, North Korea and the South China Sea, according to the sources. 