The okinawa Kaichu Road connects Yakena in Yonashiro Town and Henza Island. It is a road on the sea whose length is 4.7 kilometers, the longest of its kind in Asia. The road was constructed by Gulf Oil Company in 1971 with 900 million yen and took only thirty-three days to complete. The oil company also reclaimed a large tract of land between Henza Island and Miyagi Island to build oil tanks for emergency use. The building of the tanks was done under Japanese Government guidance.

However, fishermen and some residents protested the building of the tanks for a long time. They were afraid fishing grounds would be destroyed and the ocean would be polluted by the reclamation and the traffic of oil tankers.

Islanders used to get to the main island by walking during low tide, but when they and the Yonashiro municipal government agreed to have the oil tanks in Henza and construct a road over the ocean, transportation between the small islands and the main island became more convenient.