The governor of Tokyo has visited a group of tiny Pacific Ocean islands to highlight their strategic value.
Mr Ishihara kissed a slate which states Japan's claim to the islets
Governor Shintaro Ishihara, known for his outspoken nationalist views, wants to increase economic activity on the rocky Okinotori islands.
Japan says they are Japanese territory, with exclusive territorial waters.
But China says they are barren rocks which, under international law, cannot be used to claim exclusive economic rights over the surrounding sea.
The visit comes as relations between East Asia's two most powerful countries have been damaged by a number of disputes.
The Okinotori coral reefs lie 1,800km (1,125 miles) from Tokyo and the waters around them are rich in oil and other resources.
Mr Ishihara has said he wants to begin economic activities there, to bolster Japan's claim to the surrounding waters.
Under the United Nations Convention on the Law of the Sea, "rocks which cannot sustain human habitation or economic life of their own shall have no exclusive economic zone".
The Japanese government is planning to erect a signpost on the islands and build a helipad.
More substantial settlement is difficult because only a patch of rock the size of a tennis court remains above water at high tide.
Mr Ishihara has also talked of building a lighthouse or power station.
Earlier this year he funded expeditions there by fishermen and scientists.
The BBC's Tokyo correspondent, Jonathan Head, says Japan has spent hundreds of millions of dollars fortifying the islands with concrete, to prevent them being completely washed away.
Now a wealthy Japanese foundation is funding research into making the island's coral grow a lot faster, in the hope that a few decades from now Okinotori may look more convincingly like islands and not just rocks - as China describes them now.
Mr Ishihara's visit to Okinotori comes ahead of planned talks between Japanese Prime Minister Junichiro Koizumi and Chinese Vice Premier Wu Yi next week. They are expected to address the countries' recent troubled ties.
Violent anti-Japanese demonstrations flared in several cities across China last month, sparked by allegations Japan was glossing over its abuses during World War II.
The two countries also have long-running territorial disputes over a chain of islands in the East China Sea, known as Senkaku in Japan and Diaoyu in China. There are important gas resources in the area.