Japan's chief government spokesman welcomed the news of yet another bit, however tiny, of new territory.
"This has happened before and in some cases the islands disappeared," Yoshihide Suga said when asked if the government was planning on naming the new island.
"If it becomes a full-fledged island, we would be happy to have more territory."
The Japanese archipelago has thousands of islands. In some cases, they help anchor claims to wide expanses of ocean overlying potentially lucrative energy and mineral resources.
Japan has plans to build port facilities and transplant fast-growing coral fragments onto Okinotorishima, two rocky outcroppings even further south of Tokyo, to boost its claim in a territorial dispute with China.
