The Kuril Islands sit between Hokkaido in northern Japan and Russia's Kamchatka Peninsula. Four of the southernmost islands are claimed by Japan, which calls them the Northern Territories. Russia administers them. At the end of World War Two, the Soviet Union annexed the island chain and deported around 17,000 Japanese residents. During his visit, Putin sampled fish roe and spoke to island locals, Russian state media reported. Speaking from the prime minister's office on Thursday, Takaichi said his trip "wounds the feelings of the Japanese people" and is "incompatible with Japan's consistent position on the Northern Territories". "I hope that the Russian side will take the gravity of this matter very seriously," she said. Earlier that day, Japan's foreign minister Toshimitsu Motegi said the islands were "inherently Japanese territory both historically and under international law, and the Government of Japan strongly protests this visit".