Located in Innoshima, Onomichi City, Hiroshima Prefecture, Innoshima Suigun Castle is the only naval museum in Japan that introduces the history and culture of the Murakami Suigun (Innoshima Murakami clan), who were active in the Seto Inland Sea during the Warring States period. The imposing building was built to resemble a pirate's castle at the time, and is a must-see for castle fans and history enthusiasts. Inside the museum, weapons, ancient documents, and ship models actually used by the Murakami Suigun are on display, allowing visitors to learn in depth about how they controlled maritime traffic in the Seto Inland Sea and how they fought their way through the Warring States period.

The Suigun Castle exhibits not only documents, but also dioramas that recreate the life and battles of the time, making it easy to understand and enjoyable to visit visually. You will be overwhelmed by the intricate construction and power of the armor on display. In addition, from the observation deck on the top floor, you can see the Innoshima Bridge and the beauty of the Seto Inland Sea, and feel the expanse of the sea at the time when the Murakami Suigun was active.

The castle itself does not have any historical value, but it is an interesting place to learn about the history of the Murakami Navy, which dominated the area from the Nanboku-cho period through the Muromachi and Sengoku periods.

The Navy Festival is held here in late August.