Honjima Island

What to know

Honjima (本島) is the second largest and most developed island in the Shiwaku archipelago, a group of nearly 30 small islands in western Kagawa Prefecture. For centuries, the Shiwaku Islands played a key role in maritime trade across the Seto Inland Sea. Honjima served as the political and administrative center of the islands, and several well-preserved historical sites from that era remain.

At its peak, Honjima was the home base of the Shiwaku Navy (Shiwaku Suigun), a league of highly skilled sailors who controlled the Shiwaku Islands. In the late 1500s, Toyotomi Hideyoshi enlisted them for campaigns in Kyushu and Korea, and later granted them official governing authority over the islands.

In this role, the Shiwaku Suigun facilitated regional trade and handled government affairs on behalf of the shogun from their office near Honjima Port. The former government office (Shiwaku Kinbansho) has been preserved and is open to visitors, displaying relics such as their official seal and the logbook of the Kanrin Maru, the first Japanese ship to cross the Pacific.

Along Honjima's northeastern coast lies Kasashima Town, a beautifully preserved port town that thrived as a trade and shipbuilding center during the Edo Period (1600–1868). About twenty wooden townhouses have been preserved along narrow stone streets. Most are private homes, but three are open to the public and showcase historical household items.

A short walking trail leads up the hill east of town to the ruins of Kasashima Castle (also known as Higashiyamajo), a castle from the Warring States period (15th–16th centuries) that once commanded sweeping views of the Seto Inland Sea. Unfortunately, only a monument marks the site of the keep, and the views are now obscured by forest growth.

Other attractions on Honjima include Meotogura ("couple warehouse"), a uniquely constructed warehouse, and the former Mizumiiro Elementary School, which served as the set for the 2004 movie "Kikansha Sensei." Both are located on the island's western coast. There are also several temples, shrines, and beaches scattered around the island.