Samurai of the Seas: Japan’s Enduring Maritime Legacy

Abstract

This analysis explores Japan’s maritime power, examining how its profound knowledge of the sea has historically shaped the nation into a maritime, port, and territorial power. From its ancient seafaring traditions to its modern naval strategies, the Land of the Rising Sun has always drawn strength from the sea. Today, this enduring maritime awareness makes Japan a strategic ally for Western countries, an island nation whose connection to its surrounding waters has never been forgotten. As the Japanese saying goes、「海はすべてを知っている」“Umi wa subete o shitte iru” – "The sea knows everything."  This reflects the intimate relationship between the Japanese people and the ocean. Japan’s history is inseparable from the sea, and the sea, in turn, is inseparable from Japan’s destiny. This bond is also reflected in the code of the Bushidō, the way of the warrior, which emphasizes discipline, loyalty, and harmony with one’s environment. As written in the Hagakure: "The Way of the Samurai is found in death" or "Bushidō wa shinu koto to mitsuketari", but also in living with awareness, just as navigating the sea requires presence, courage, and respect.

Historical and Cultural Foundations

In the Japanese language, the word for "sea" 海 (umi) is more than a geographical term. Composed of the water radical (氵) and the character 毎 (mai, meaning "every" or "always"), its very structure suggests omnipresence and continuity. Umi evokes not only physical water but a deeper existential element: it represents life, danger, mystery, boundaries, and belonging. It is a linguistic centrality and richness throughout Japanese culture. Words like 海神 (kaijin or watatsumi) god of the sea, 海流 (kairyū) ocean current, 海岸 (kaigan) coastline, and 海風 (umikaze) sea breeze, form a semantic map that reflects how embedded the sea is in the national consciousness. Japan’s maritime consciousness is ancient and deeply spiritual. In Shintō belief, the sea is inhabited by deities, foremost among them, Watatsumi, the dragon god of the ocean. Fishermen and coastal communities have long viewed the sea as both a source of nourishment and a sacred force to be respected. Rituals, shrines, and pilgrimages to sea-bound islands like Itsukushima underscore the spiritual bond between the Japanese people and the waters that surround them. From its earliest history, Japan was formed by and through the sea. Archaeological evidence from the Jōmon period (c. 10,000–300 BCE) shows a rich maritime diet and advanced fishing techniques, including dolphin and tuna hunting. Migration, trade, and cultural exchange; especially with China, Korea, and Southeast Asia, occurred overwhelmingly by sea. Japan’s early religious and artistic forms were shaped by maritime connections and influence. Despite this openness, Japan’s geography also encouraged insularity and isolationism. The Tokugawa shogunate (1603–1868) imposed strict controls on foreign contact, leading to centuries of relative seclusion. Yet, this archipelagic isolation was not purely defensive; it fostered the development of a distinctive, internally coherent culture, deeply attuned to seasonal cycles, coastal rhythms, and regional variation from Hokkaidō (Nord) to Okinawa (South). From north to south, the Kuroshio and Oyashio currents, monsoon winds, and ocean geography shaped cultural, linguistic, and even genetic differences across the islands. No part of Japan is more than 150 km (93 miles) from the sea. The surrounding waters: the Pacific Ocean, the Sea of Japan, the East China Sea, and the Sea of Okhotsk not only influenced Japan’s diet and economy, but its national psychology: what some Japanese call the shimaguni konjō (島国根性), or “island nation mentality”. It reflects both a sense of separateness and a powerful unity shaped by geography and the ocean. This is an undeniable part also of the knowledge, shared through centuries, of the sea. The sea has served not just as a commercial bridge, but also defined military perception, threat assessment, and strategic planning. As Japan rapidly reformed its naval forces, drawing direct inspiration from the British Royal Navy, it also recognized that human capital would be central to national strength. One emblematic figure of this era was Kenjiro Yamakawa, a former samurai of the Byakkotai who had once resisted the new imperial government. Rather than being cast aside, Yamakawa was entrusted with the future: appointed President of the Imperial University of Tokyo, he embodied the Meiji belief that "the strength of a country lies in its people". This evolution was not only technical but also conceptual: the belief emerged that maritime control was essential for national security: borders, maritime straits and control of resources. The Battle of Tsushima (1905), in which the Japanese Navy decisively defeated the Russian fleet, became the ultimate symbol of this awareness.

Present Maritime Power

Generational knowledge of ocean currents, coastal geography, and shipping lanes translated into tactical superiority. Centuries of experience from fishermen and traditional navigators were integrated into the education of Japanese naval officers. As highlighted in the ISPI report by Axel Berkofsky and Sergio Miracola: Japan has long emphasized maritime domain awareness, developing capabilities to monitor and defend its sea lanes of communication (SLOCs), which are vital for an island country reliant on imports for energy and raw materials. Following World War II, Japan’s pacifist constitution (1947) restricted the use of military force. However, the country invested heavily in developing the Japan Maritime Self-Defense Force (JMSDF) or Kaijō Jieitai, part of the Japan Self-Defense Forces or Jieitai. Today, it stands among the world’s most technologically advanced navies, with strengths in:

●      Maritime surveillance and intelligence

●      Asymmetric defense (e.g., against submarines and missile threats)

●      Power projection across the Indo-Pacific region

As part of its Defense Buildup Program, aligned with the newly defined National Defense Strategy, Japan is set to dramatically strengthen its Multi-Domain Defense Force. This force will combine capabilities across space, cyber, and electromagnetic domains to create an integrated, resilient system capable of sustained, strategic operations, from peacetime to full-scale conflict. The modernization plan emphasizes adaptability to new forms of warfare and adversaries' evolving capabilities. By Fiscal Year 2027, Japan aims to possess the capacity to take primary responsibility for defending its territory, with the ability to detect, disrupt, and defeat potential invasions, while working closely with allies. To launch this ambitious transformation, the government has allocated the necessary resources in the 2023 defense budget, marking the first year of implementation for this comprehensive upgrade of Japan’s national defense capabilities. Japan’s defense posture increasingly hinges on a robust, innovation-driven industrial base. Viewing technology as a core element of national security, Tokyo is investing heavily in next-generation defense R&D through a whole-of-government approach. By bridging private sector innovation with military needs (especially in AI, cybersecurity, and aerospace) Japan aims to create a sustainable model of dual-use technological advancement. Initiatives to streamline public-private collaboration and reform export controls also signal a clear pivot toward proactive defense diplomacy, particularly in the Indo-Pacific. Japan’s naval power is concretely found in the Sōryū‑class attack submarines, a cornerstone of the Japan Maritime Self‑Defense Force’s undersea fleet. Commissioned beginning in 2009, this twelve‑boat class marks Japan’s first operational use of Air‑Independent Propulsion (AIP) via Swedish‑licensed Stirling engines built by Kawasaki Heavy Industries, enabling exceptionally quiet operation and extended submerged endurance, greatly enhancing stealth and survivability in contested waters. Armed with Type‑89 torpedoes and UGM‑84 Harpoon anti‑ship missiles, the Sōryū‑class enforces formidable undersea deterrence in the Western Pacific.

Equally significant, Japan has fielded the Type 12 Surface‑to‑Ship Missile (12 SSM), developed by Mitsubishi Heavy Industries. It comes from a land weapon managed by the land forces. It replaces the earlier Type 88, using inertial navigation with GPS mid-course guidance and a terminal Ka‑band AESA radar seeker. Its improved low-RCS design allows ranges of 200 km initially, with upgraded variants extending to 900–1,000 km or more, and planned ship‑ and air‑launch versions deployed by FY2027.

These are just two examples of the high quality and system integrations among the JMSDF.

Geoeconomics and Strategic Outlook

Like the Roman, Greek, and British Empires, Japan, one of the longest-standing empires in history, possesses deep knowledge in managing the sea and understanding the surrounding maritime territory. This makes the country an irreplaceable strategic asset for its allies. Japan’s cultural and geographic maritime legacy continues to influence its operational doctrines, emphasizing mobility, environmental adaptability, and intelligent use of its rugged coastal terrain. Japan’s “maritime mind” is not merely a matter of cultural identity or commerce, it remains a core strategic pillar of its national defense, especially in the face of rising regional tensions such as Chinese expansionism and territorial disputes in the East China Sea.  This historical maritime literacy makes Japan an irreplaceable strategic partner for Western allies. Its cultural and geographic legacy at sea continues to shape military doctrine, emphasizing mobility, resilience to natural environments, and the intelligent use of coastal topography. Beyond military strategy, Japan’s geoeconomic role is increasingly central to the Indo-Pacific architecture. As the world’s fourth-largest economy and a major global trading power, Japan is critically dependent on secure sea lanes of communication (SLOCs) to import over 90% of its energy and raw materials. The East and South China Seas, where many of these SLOCs pass, have become contested zones, particularly amid Chinese naval assertiveness and gray-zone operations. In response, Tokyo has begun to integrate economic security into its national defense posture. This includes investments in resilient supply chains, protection of undersea cables, and greater maritime surveillance capabilities. The 2022 National Security Strategy outlines Japan’s intent to “preserve strategic stability” through geoeconomic tools, including economic partnerships, critical infrastructure safeguards, and cooperation in key domains like semiconductors and rare earths. The “maritime mind” is thus no longer just a matter of tradition or identity, it represents a strategic axis of survival in an era of multipolar competition. From Tokyo to Okinawa, the country's coastline is both its first line of defense and the backbone of its economic security. As climate change, technological shifts, and great-power rivalry reshape the maritime domain, Japan’s dual emphasis on military readiness and economic resilience positions it as a crucial shaper of the Indo-Pacific order. Without Japan’s maritime vigilance and geoeconomic foresight, how would the West safeguard its interests and maintain stability in the Indo-Pacific?