* Image is for illustrative purposes only.Iimori Mountain Castle
飯盛山城
Iimori Mountain Castle is a historic castle in Kansai dating from the Tenbun era (mid-16th century, ca. 1532–1555) expansion, whose lord was Kizawa Nagamasa / Miyoshi Nagayoshi.
Overview
Miyoshi Nagayoshi's Base of Power for Ruling the Realm
Iimori Mountain Castle is a yamashiro (mountain fortress) built on Iimori Mountain at an elevation of 314 meters, spanning Daito City and Shijonawate City in Osaka Prefecture. It is known as the greatest seat of power when Miyoshi Nagayoshi held dominion over the realm during the mid-16th century. Originally, it began as a fortification established by Kizawa Nagamasa during the Daiei era, but Miyoshi Nagayoshi's large-scale expansion and reconstruction during the Tenbun era (ca. 1532–1555) transformed it into one of the largest yamashiro in the Kinai region.
Miyoshi Nagayoshi and Japan's "First Unifier"
Miyoshi Nagayoshi is a military commander often described in Japanese history as the "first unifier." In Tenbun 18 (1549), Nagayoshi severed his vassal relationship with Hosokawa Harumoto and effectively placed the powers of the Kanrei (shogunal regent) under his control. The following year, Tenbun 19 (1550), he expelled Shogun Ashikaga Yoshiteru from Kyoto. By Tenbun 22 (1553), he had gained complete dominion over Kyoto alongside the Miyoshi Sandai-no-Shu (his three principal retainers). While the Muromachi Shogunate retained nominal authority during this period, Miyoshi Nagayoshi was the effective political ruler of Japan and became a precursor to Oda Nobunaga's later centralized military unification (tenka bugyō). While basing himself at Iimori Mountain Castle, Nagayoshi controlled the commercial city of Sakai and monopolized profits from Southern Barbarian (Nanban) trade, ruling the Kinai region through accumulated wealth and military might.
The Structure of Iimori Mountain Castle
Iimori Mountain Castle is a classic Sengoku-period yamashiro that maximized the ridge terrain, featuring multiple kuruwa (enclosures) arranged in tiers from the summit down the mountainside, creating a complex defensive system. The main enclosure (honmaru) at the summit was flanked by the demaru (outer enclosure), ninomaru (second enclosure), and sanomaru (third enclosure) arrayed along ridges extending east-west-north-south, spanning approximately 1 kilometer in total length. Recent excavations have revealed stone-wall ruins on an unexpectedly large scale, confirming that high ashlar stone walls extended throughout the fortress. This stone-wall construction technique is noted as potentially influencing the later construction of Azuchi Castle.
Shijonawate and the Memory of the Sengoku Period
The foothills of Iimori Mountain, Shijonawate (四條畷), is also known as the site of the Battle of Shijonawate in Shohei 3 (1348) of the Northern and Southern Dynasties period, where Kusunoki Masatsura was defeated by the great army of Kō Moronao. Masatsura, the legitimate son of Kusunoki Masashige, inherited his father's cause and fought for the Southern Dynasty (Nanchō), meeting a glorious end at this location. Two centuries after the turmoil of the Northern and Southern Dynasties, the same Iimori Mountain ground saw a new power holder, Miyoshi Nagayoshi, dominating the Kinai region—a poignant reminder of history's causality. Today, Shijonawate Shrine houses a sanctuary dedicated to Kusunoki Masatsura, and together with the Iimori Mountain Castle ruins, it offers historical tourism centered on the theme of "loyalty" (chūgi).
Connection to Swords
Miyoshi Nagayoshi's Iimori Mountain Castle and sword culture are conveyed through their close ties with Sakai, a special city. Nagayoshi placed Sakai under his effective control and invested the wealth obtained from Southern Barbarian trade into all aspects of politics, military, and culture. Sakai was also an important hub in the distribution of Japanese swords at that time, and renowned blades from Bizen, Sōshū, Yamashiro, and other regions were distributed nationwide through the hands of Sakai merchants. Nagayoshi is said to have been enthusiastically devoted to collecting famous swords to demonstrate his martial prowess, and daimyo under Miyoshi command wore swords by master smiths from various regions. In particular, Matsunaga Hisahide, Nagayoshi's chief retainer, was known as a person of artistic sensibility and owned numerous masterpieces of tea vessels and swords. Matsunaga Hisahide is famous for the anecdote of repeatedly refusing Oda Nobunaga's requests for the celebrated tea bowl known as the Hira-Kumo (Kō-Temyō Hira-Kumo), though he presented tea-ceremony treasures such as the Ninety-nine Hair Nasu, and was also known as a connoisseur collector of acclaimed blades. The Kinai region during the period of Miyoshi rule was recovering from the turmoil following the Ōnin War, and it was also an important time when sword smiths again settled in cities and resumed their craft.
Highlights
- Summit Honmaru Ruins and Stone-Wall Remains — massive stonework confirmed by recent excavations, significantly larger than previously expected
- Mountain Trail (Iimori Mountain Hiking Course) — panoramic views overlooking the Osaka Plain and Ikoma Mountain Range
- Shijonawate Shrine — sacred site of the Northern and Southern Dynasties era, enshrining Kusunoki Masatsura, located near the Iimori Mountain Castle ruins
- Shijonawate City Historical and Folk Museum — displays excavation materials from Miyoshi Nagayoshi and Iimori Mountain Castle
- Northern and Southern Dynasties-Related Historic Sites — location of the Battle of Shijonawate and the site of Kusunoki Masatsura's final stand
* Opening hours and admission fees are subject to change. Please check the official website before visiting.