At last count, Japan was in severe dispute with every one of its neighbors — Russia, South Korea, North Korea, China and Taiwan. Blame Tokyo's mishandling of issues if you wish. But blame also the legacy of the region's immediate postwar history. The dispute with Russia is a good example.
In February 1945, to persuade Moscow to join the still unfinished war against Japan, the United Kingdom and the United States at Yalta promised Moscow it could take Japan's Kuril Islands as a reward. Moscow gladly seized that reward. And in the 1951 San Francisco peace treaty negotiations the U.S. seemed to confirm that Yalta promise by forcing Japan to renounce all rights, claim and title to the Kurils.
In 1954, Tokyo began to insist that Moscow should at least return Shikotan and the Habomais, islands separate from the Kurils and close to Hokkaido that Soviet troops had also seized at war end. Moscow said yes, but when Tokyo then demanded the return of the two southernmost Kurils islands — Etorofu and Kunashiri also close to Japan — Moscow said no.