Buckle up, everyone. Today, we’re diving into a group I’ve been itching to feature on this blog for what feels like forever. Known today as the Murakami Suigun, this band of seafaring warlords were basically Japan’s answer to pirate lords, ruling the waves of the Seto Inland Sea from their island strongholds in what’s now Ehime Prefecture. Yes, you read that right. Japan had pirates. And not just a handful of salty rogues either, but an entire maritime force that dominated regional waters for centuries. The Murakami were the main event in that long, often-overlooked chapter of Japanese history.
On that note, we’re going to be using the word pirate a lot in this article. For readers hailing from Western cultures, this might conjure up images of eye patches, frilly shirts, and rum from the Golden Age of Piracy. But Japan’s variant of these ruffians was a bit different. As was the case in most of the world across the long arc of history, piracy wasn’t a full-time job. Instead, it was more of a side endeavor that many coastal populations took up when the opportunity presented itself. Yes, this even applied to groups like the Vikings and the Barbary Corsairs.
Now, brace yourself for a shocker of National Geographic-level insight: Japan is, in fact, an island nation. Naturally, as those of us who’ve spent any time poking around in the past might already grasp, it follows that Japan has long had its fair share of part-time pirates operating along its edges. Dig into records from mainland powers and you’ll often find frustrated notes about weapons and supplies being plundered by seafaring raiders. Of course, whether these Wako sea bandits were “Japanese” in the way we understand the term today is still very much up for debate. But I digress.
That all said, it’s important to remember that piracy was only ever a part-time gig. When the sea wasn’t serving up the right opportunities to engage in what might just be one of the oldest hustles in human history, savvy sailors had to pivot. Luckily, their skills weren’t exactly niche. These folks often found other ways to make a living that played to what they already knew: how to navigate, intimidate, and control a patch of ocean. Whether it was shipping, offering protection from rival pirates (for a fee, of course), or dabbling in straight-up racketeering, the pirates around Japan evolved along a very different path than the rum-soaked caricatures of Jack Sparrow fame.
This now brings us to the Murakami Suigun. Operating in and around the Seto Inland Sea during Japan’s chaotic Warring States period (1467–1600), this naval force was less a ragtag gang of cutthroats and more a loosely affiliated maritime dynasty with serious military chops. The group was composed of three families, each based on a different island: Noshima, Innoshima, and Kurushima. Together, they built a reputation as some of the most formidable seafarers Japan had ever seen. Whether enforcing tolls, guiding merchant vessels through treacherous currents, or flexing naval muscle during full-on battles on behalf of the daimyo on land, the Murakami weren’t just surviving at sea; they were ruling it.
The three branches of the clan each operated independently while maintaining blood ties and occasionally teaming up when the politics or the loot made it worth their time. The Innoshima Murakami were based in what is now Hiroshima Prefecture, while the Kurushima held territory further south around modern-day Oshima. But of the three, the Noshima Murakami stood out as the most influential, and they also happen to be my personal favorite for their cunning ruthlessness. Stationed on a small, rocky island right in the middle of the Seto Inland Sea’s central shipping lanes, they were perfectly positioned to run what was essentially maritime traffic control for feudal Japan.
What set the Noshima Murakami apart wasn’t just geography. It was their ability to play both pirate and protector depending on which way the political winds were blowing during the blood-soaked years of Japan’s civil war. Under the leadership of figures like Murakami Takeyoshi, they rose to become key players in regional conflicts. They often aligned with powerful clans like the Mori, not out of loyalty but as a calculated move, while also playing the other side at the same time. These weren’t backwater raiders. They were naval tacticians capable of organizing large-scale fleet maneuvers and laying traps that could flip the outcome of an entire battle.
It’s also worth noting that the rise of the Murakami Suigun didn’t happen in a vacuum. It came in the power vacuum left by the crumbling Ashikaga shogunate. As central authority weakened in the late 1400s and Japan slipped into an era of chaos, the space for local warlords and seaborne powerbrokers widened significantly. With no strong hand to govern the coastal fringes or enforce maritime law, groups like the Murakami stepped in to fill the void. They didn’t just thrive in the absence of oversight; they effectively became the oversight, controlling trade, exacting tolls, and enforcing their own rules in waters the shogunate could no longer reach.
Of course, even the best-run pirate empires have an expiration date. By the late 1500s, Japan was moving toward unification under Toyotomi Hideyoshi, and independent naval powers like the Murakami no longer fit into the national vision. In 1588, Hideyoshi issued a sweeping ban on piracy that effectively ended the Murakami’s reign on the waves. Some of them pivoted into official roles, serving as retainers or minor lords, but their golden era had clearly passed. Still, their story lives on in castle ruins, museum exhibits, annual festivals, and the lingering lore that clings to the salt air of the Seto Inland Sea.
How to Get There
Now that we’ve covered the history of the Murakami Suigun, let’s take a quick breather and look at the logistics of actually experiencing what’s left of their legacy today. One of the reasons it took me so long to visit the sites associated with this legendary group of Japanese pirates is because they’re scattered across the Shimanami Kaido, a chain of islands connecting the port town of Onomichi on Honshu with the city of Imabari on Shikoku. While there are a few bus options, this stretch is best explored by bicycle or rental cart.
How you choose to get around the Shimanami Kaido is totally up to you. I won’t derail this article any further, other than to note that there are plenty of bike rental options on both sides of the Seto Inland Sea if driving isn’t in the cards. That said, if you’re serious about diving into Murakami Suigun lore, it’s best to take your time and plan on tackling the Shimanami Kaido over a few days. There’s simply too much to see in one go, with several historical sites scattered across the islands that once made up the Suigun’s maritime domain.
As for how to get to the region, that really depends on where you’re coming from. Most people begin their journey in Onomichi and cross over the islands toward Imabari, but the reverse route works just as well. I recommend using a service like Jorudan to plan your train and bus connections. The most straightforward option is to take the bullet train to Fukuyama Station, then transfer to a local train to Onomichi, where you can grab a bus or rent a bike. That said, it’s not a one-size-fits-all route, so be sure to check your options and plan accordingly.
The Murakami KAIZOKU Museum
No place does a better job of unpacking the story of the Murakami Suigun than the Murakami KAIZOKU Museum. Located in Imabari on the island of Oshima , this three-floor facility offers a deep dive into the life and times of Japan’s most famous pirates. The museum originally opened in 2004 under the name Murakami Suigun Museum, but was rebranded in 2020 to emphasize the more culturally loaded term kaizoku. Inside, the museum curates an impressive lineup of exhibits that trace the rise, reign, and eventual decline of the Murakami maritime empire. Whether you’re a hardcore history nerd or just mildly pirate-curious, this spot is well worth a stop.
The exhibits span three floors and cover everything from ship models and excavated relics to samurai armor and historical documents. On the first floor, you’ll find a library, lecture room, and gift shop, along with a cafeteria for anyone needing a break. The second floor hosts the main exhibition space, where you can explore the sea battles of the Murakami, check out artifacts from Noshima Castle excavations, and even watch a short documentary on their naval strategies. The real highlight, however, is up on the third floor: a panoramic observation gallery that looks out over the ruins of Noshima Castle and the very waters the Murakami once ruled. It even includes a satellite floor map of the Shimanami Kaido, giving you a bird’s-eye view of the entire area.
Getting to the museum is easy if you’re already making your way along the Shimanami Kaido. It’s located just off the main route on Oshima and is accessible by bike, bus, or car. If you’re cycling, there’s bike parking on-site. If you’re coming by bus, the nearest stop is just a short walk away. Admission is reasonably priced at 350 yen for adults, with discounts for students, children, and groups. For those who really want to take their time, there are interactive zones inside the museum where you can try on armor or explore models hands-on, which is perfect for both kids and curious grownups alike.
By the way, if you’re curious about the museum’s rebrand, here’s the deal: the Murakami Suigun weren’t always referred to as Suigun, which translates to “navy.” Originally, they were known more commonly as Kaizoku, meaning “sea bandit” or “pirate.” However, in the lead-up to the Edo period, the Murakami clan strategically reframed their legacy, emphasizing their role as a legitimate maritime force rather than a gang of raiders. This shift in terminology wasn’t just semantics — it was savvy PR. By aligning themselves with the land-based lords who ultimately unified the country, the Murakami were able to secure a more honorable place in the historical record.
The Castle on Noshima
To really grasp the story of the Murakami Suigun (and, by extension, the other lesser-known pirate groups that once prowled the Seto Inland Sea), you first need to understand what makes this body of water so unique. At a glance, the sea might look serene, dotted with picturesque islands and gently bobbing fishing boats. But don’t let that calm exterior fool you. Beneath the surface, it’s a complex and dynamic environment that shaped the strategies and power structures of every group that dared to navigate it. In fact, it wouldn’t be a stretch to say that the tides of the Seto Inland Sea helped shape the culture and history of the entire region, giving rise to port towns like Tomonoura and leaving a legacy that still defines it today.
For those unfamiliar, the Seto Inland Sea has only four natural entry points, which means water rushes in and out with every tide cycle. This creates one of the most extreme tidal differentials in the world, with changes sometimes reaching a jaw-dropping three meters. The currents shift rapidly depending on the time of day and season, forming chokepoints and whirlpools that would easily throw off any outsider. Knowing how to read the water here wasn’t just helpful — it was essential. And if you did know how to work the tides to your advantage, you could dominate this stretch of sea like few others in history.
Despite its relatively protected geography, the Seto Inland Sea can be surprisingly treacherous if you don’t know what you’re doing. This isn’t open-ocean sailing, and the dangers aren’t always obvious. But if you’re not careful, the tides will take you to places you weren’t planning to go, like a jagged rock formation for example. The Murakami, especially the Noshima branch, mastered this ever-changing environment, turning it into a natural moat that protected their floating empire. Their intimate understanding of the tides, currents, and narrow straits is one of the key reasons they were able to thrive for so long. These weren’t just pirates — they were oceanographers with a pirating side hustle.
Nowhere is this mastery better demonstrated than at the seat of power of the Noshima Murakami: Noshima Castle. Located just off the coast from the modern-day Murakami KAIZOKU Museum, this was a fortress built across two small islands, Noshima and Taizakijima. The idea of constructing a castle on the sea was almost unheard of in Japan, but the Noshima Murakami pulled it off. The strong currents surrounding the island acted as a natural bulwark, and the strategic positioning allowed them to control marine traffic in every direction. Modern archaeologists have even uncovered luxury items like imported Chinese and Korean ceramics, suggesting that this was more than just a military base — it was a center of status and administrative clout.
If you’re itching to see the ruins of Noshima Castle for yourself (and you absolutely should), boat tours are available from just outside the museum. The ride takes you around the perimeter of what was once a maritime stronghold, giving you a firsthand look at the kind of terrain the Noshima Murakami turned into their fortress and the powerful tides that still swirl around it. It’s one thing to read about their brilliance, but quite another to see the currents with your own eyes and realize just how well these so-called pirates knew the sea they ruled.
Sacred Oyamazumi Shrine
In addition to the Murakami KAIZOKU Museum and the ruins of Noshima Castle, one other must-see spot related to this historic group of sea lords is Oyamazumi Shrine. Located on Omishima, this ancient shrine was the spiritual center of the Seto Inland Sea. Dedicated to Oyamazumi, the god of mountains, the sea, and war, it has long drawn warriors, sailors, and anyone looking to hedge their bets before heading into battle. Naturally, the three families that comprised the Murakami Suigun were regular visitors. If you were making your living on these waters, you paid your respects here. That was just common sense in the Setouchi region.
What’s particularly striking about the Murakami Suigun’s relationship with Oyamazumi Shrine is how they wove it into their identity. These weren’t just pirates hoping for lucky tides and a wayward ship to plunder. They were spiritual operators as well. In fact, the Noshima Murakami, in particular, offered linked poetry called horaku renga as ritual prayers, asking for safe voyages and military success. They even adopted the shrine’s crest as part of their own. This wasn’t just a shrine to the Murakami Suigun — it was their divine protector.
In addition to its ties to the Murakami Suigun, Oyamazumi Shrine is also home to one of the most impressive collections of samurai arms and armor in the entire country. The treasure hall features gear donated by warriors over the centuries, including some said to belong to Ohori Tsuru-hime, the legendary “Joan of Arc of Japan” who had close ties to the Murakami families. Roughly 40 percent of Japan’s swords and armor designated as National Treasures or Important Cultural Properties are housed here. If you’re into samurai lore, this place is absolutely stacked.
Even if history isn’t your thing, the grounds themselves are worth the stop. Massive camphor trees, some thousands of years old, tower over the mossy paths, and the whole place feels like it has been quietly watching over the sea for ages. For the Murakami Suigun, Oyamazumi wasn’t just a holy site — it was part of the infrastructure that made their maritime empire possible. Between this and Noshima Castle, you begin to understand just how much influence the Murakami Suigun truly wielded over the Seto Inland Sea.
Innoshima Suigun Castle
The ruins of Noshima Castle may win the “most dramatic fortress location” award, surrounded by riptides and all, but that doesn’t mean you should skip a visit to Innoshima Suigun Castle. Perched high on a hilltop overlooking the Seto Inland Sea, this reconstructed castle-museum leans more theatrical than authentic, but don’t let the stylized exterior fool you. Inside, it delivers a surprisingly solid look at the naval power that once ruled these waters. It’s a worthy addition to any Murakami Suigun itinerary and adds context to the story told at the Murakami KAIZOKU Museum.
Innoshima was home turf for the Innoshima Murakami, one of the three powerful families that made up the Suigun alliance. While not quite as dominant as the Noshima Murakami, they held a crucial strategic position along the Onomichi Channel and commanded key sea routes that were vital for trade and military movement. The Innoshima Murakami were known for their tight control of local shipping lanes and their ability to coordinate with or resist rival clans depending on the situation. Their hilltop fortifications gave them an excellent vantage point to monitor the waters below, reinforcing their reputation as both pirates and protectors.
The current castle isn’t the original stronghold, which was lost to time, but it was built in the 1980s as a tribute to the naval legacy of the region. Inside, you’ll find artifacts from the Murakami Suigun’s heyday, including weapons, nautical equipment, historic documents, and detailed models of their ships. There’s also a small observation area with panoramic views of the surrounding Seto Inland Sea, which gives you a real sense of why the Innoshima branch of the Murakami chose this spot as their base of operations. It’s not as sprawling as the Murakami KAIZOKU Museum, but it packs a lot into a compact space.
Getting to Innoshima Suigun Castle is straightforward if you’re already biking or driving the Shimanami Kaido. The site is open daily from 9:30 am to 5:00 pm, and admission costs a modest 310 yen for adults and 160 yen for children. There’s free parking nearby, and for cyclists it’s only a short uphill ride from the main route. Just below the castle sits Konren-ji, the family temple of the Innoshima Murakami. With its atmospheric stone stupas and ancestral graves, it provides a quiet, reflective end to a visit that ties together the spiritual and military threads of their story.
Other Nearby Attractions
First things first, let’s cover the obvious options for more things to see and do in the region. For starters, the port town of Onomichi back on Honshu is most definitely worth your time. If you’re exploring this part of the Setouchi region by bus, you’ll almost certainly pass back through here, so plan at least a day to wander around Onomichi. Not only is it packed with temples and hillside paths, but it also has a long history as a pirate haven. And whatever you do, don’t skip the local ramen — it’s one of the city’s specialties.
Over on the Shikoku side of the Seto Inland Sea, you’ll find the city of Imabari. Best known today as the endpoint of the Shimanami Kaido cycling route, Imabari is also famous for producing some of Japan’s highest-quality towels. On top of that, it’s a treasure trove of maritime military history, being home to one of the country’s few surviving seaside castles. For those biking the Shimanami Kaido and tracing the legacy of the Murakami Suigun along the way, Imabari will most likely be where you end your journey. Of course, if you started in Imabari, then this is where your adventure kicks off.
With those options out of the way, let’s dig into a few more spots directly tied to the Murakami Suigun. That brings us to the branch of the trio of families we’ve yet to cover — the Kurushima Murakami. Unlike the sites linked to Noshima and Innoshima, there isn’t much left of their legacy in terms of ruins or reconstructed castles. Still, that doesn’t mean they didn’t play a vital role in shaping the history of the Seto Inland Sea. Their control of the southern routes was critical in maintaining dominance over the region, and the Suigun as a whole would not have been as strong without them securing the southwestern edges.
The Kurushima Murakami were based on Oshima, just off the coast of Shikoku near modern-day Imabari. From this vantage point, they commanded the narrow straits that funneled ships moving between Honshu and Kyushu, making them indispensable power brokers. Like their cousins on Noshima and Innoshima, the Kurushima Murakami alternated between piracy, naval enforcement, and political alliances depending on the situation. Their influence was so strong that even powerful warlords had little choice but to negotiate with them if they wanted safe passage.
Today, there’s little in the way of preserved strongholds to mark their presence, but traces of the Kurushima Murakami can still be felt in the region. The nearby Kurushima Kaikyo Bridge, the longest suspension bridge in the world, takes its name from their legacy and spans the same turbulent waters they once controlled. While you won’t find a dedicated museum here, simply crossing this impressive stretch gives you a sense of the challenges the Murakami once mastered. It may be less tangible than the ruins of Noshima Castle, but the Kurushima story is still written into the straits that bear their name.
Additionally, there are plenty of other spots along the Shimanami Kaido tied to the Murakami Suigun. In fact, Japan has officially enshrined as many as 43 sites as a collective of Important Cultural Properties connected to the pirates of the Seto Inland Sea. Some of these locations are more engaging than others, but the sheer number shows just how deep the Murakami footprint runs in this region. While making the rounds to all of them would be a challenge, it’s worth checking out what’s on offer and weaving a few into your itinerary.
One standout for me was the 500 Rakan statues atop Mt. Shirataki. Located just north of Innoshima Suigun Castle on the island of Innoshima, this site is said to have been created by Murakami Yoshimitsu of the Innoshima Murakami branch of the clan. The statues are dedicated to the bodhisattva Kannon, the Buddhist deity of mercy, and the sight of row after row of stone figures is absolutely breathtaking. The photo above gives you a taste of the setting, but standing there in person, gazing out at the sea lanes far below while surrounded by these weathered guardians, is an entirely different experience.
Finally, the region continues to celebrate the Murakami Suigun’s legacy with annual festivals that bring their story to life in spectacular fashion. The most famous is the Innoshima Suigun Festival, held every summer on Innoshima. Locals dress in period armor, reenact naval battles, and parade through the streets in honor of their seafaring ancestors. The event features everything from taiko drumming to mock pirate skirmishes on the water, offering a glimpse into the pageantry and pride that the Murakami Suigun still inspire today. If your timing lines up, it’s the perfect way to experience a living connection to these legendary lords of the Seto Inland Sea.
Until next time travelers…
