Japan’s trade watchdog plans to instruct Google LLC to reform its business practices after finding that it may have imposed unfair restrictions in its search advertising agreement with Yahoo Japan, sources close to the case said Tuesday. The Japan Fair Trade Commission believes the practices by the U.S. search giant could further undermine competition in the advertising market, the sources said. Yahoo Japan, now LY Corp., has said it had no choice but to accept Google’s request because it receives ad distribution technology from Google. Google has submitted to the trade commission a plan to vo…