The Imperial Household Agency said Monday it will jointly excavate Japan's largest ancient mounded tomb with a local government for the first time.The agency had restricted such a survey in Daisen Kofun, which was first built in the fifth century and is officially designated as the tomb of Emperor Nintoku, saying the mound is "the imperial family's tomb where peace and sanctity needed to be maintained."The excavation survey starting later this month in one of the dikes surrounding the massive tomb in Sakai, Osaka Prefecture, will be part of the tomb's preservation efforts conducted with the…READ FULL ARTICLE