With all the attention being paid to the Diaoyu/Senkaku islands at the moment, it's worth keeping in mind that they aren't the only remote pacific islets that China and Japan are feuding over. And despite their much-maligned size and lack of resources (besides bat guano), the Diaoyus/Senkakus aren't even the most desolate of the ocean rocks inflaming tensions between the two Asian superpowers.
See: Okinotorishima (pictured above). This singularly unimpressive coral atoll barely remains above the waves at high tide -- and only does so thanks to human help. Japan has spent $600 million taking measures to defend Okinotorishima from the sea by encasing parts of the islets in concrete and steel. Several years ago it sent fishery officials to plant extra coral around them in an attempt to beef them up and protect them from erosion (the islets sit in a particularly stormy corner of the Pacific). Yet even so, at high tide the two chunks of the island that protrude from the water are described as hardly larger than a pair of king size beds, and remained threatened by rising sea levels.
To be clear, this fight differs from the Diaoyu/Senkaku dispute in that China does not want Okinotorishima (translated as "remote bird island"), or challenge Japan's claim. But the Okinotorishima fight highlights the geopolitics often underlying these island feuds: Japan has gone to such lengths to preserve Okinotorishima because possession of the tiny islets lets Japan claim an extra 150,000 square miles of exclusive economic zone, strategically located between Taiwan and US military bases on Guam. China - which been accused of violating Japanese sovereignty by mapping the sea floor around the islands - claims that they are not islands at all, but marine rocks, and therefore not entitled to their own EEZ (the UN Convention on the Law of the Sea says that rocks must be able to sustain "human habitation or economic life" before they get an EEZ). A recent UN panel on the issue has generated claims of victory from both sides.
At this point, the geopolitics of the Diaoyu/Senkaku fight have been mostly overshadowed by issues of historical grievances and nationalism - however, these islands, too, would give China and Japan EEZ rights to waters potentially containing significant oil and gas reserves. Similarly, the Okinotorishima fight, while at heart a geopolitical one, has occasionally also been complicated by nationalist feelings: following the Chinese crying foul over the islets in 2004, the right-learning Nippon Foundation scrambled to construct a lighthouse that would help generate "economic life", and help bolster their claim that it's morethan a reef.
While the Diaoyu/Senkaku furor is clearly top priority for the moment, Japan hasn't forgotten about Okinotorishima: earlier this year, the Cabinet approved legislation that gave the Coast Guard new law enforcement powers in some of the country's disputed territorial waters. The Diaoyu/Senkaku islands were on the list; so was Okinotorishima.