The Japan Coast Guard says a small uninhabited island off the northern prefecture of Hokkaido may have disappeared due to erosion by waves and floating ice.
NHK has learned from coast guard officials that the island named Esanbehana Kita Kojima, about 500 meters off the village of Sarufutsu in northern Hokkaido, may have vanished.
The Coast Guard received a report from residents of the village earlier in October that the island could no longer be seen.
A fisheries association sent out boats in mid-October only to find the island was missing.
The coast guard officials say there is a possibility that waves and ice floes may have worn away everything above sea level.
They say the height of the island was about 1.4 meters above sea level when a survey was conducted 31 years ago.
The Japanese government 4 years ago gave an official name to the island, which serves as the basis for the boundary of the country's territorial waters.
The UN Convention on the Law of the Sea defines an island as an area of land surrounded by water, which is above water during high tide.
The coast guard plans to carry out a detailed survey, as the apparent disappearance of the island could reduce Japan's territorial waters.