SHIRAKAWA, Gifu Prefecture--Villagers in this renowned UNESCO World Heritage site came together to re-thatch the roof of a multitiered house here for the first time in five years on May 13.

Despite offering some of Japan’s most beautiful scenery, Shirakawa-ko isn’t all that famous. “Wait a second,” you might be saying, “isn’t that village in Gifu Prefecture with the thatched roofs one of ...