* Image is for illustrative purposes only.Ishigakiyama Castle (Ishigakiyama Ichiyo Castle)
石垣山城（石垣山一夜城）
Ishigakiyama Castle (Ishigakiyama Ichiyo Castle) is a historic castle in Kantō dating from the Founded in Tenshō 18 (1590). A total-stone-fortification siege castle built by Toyotomi Hideyoshi in approximately 80 days during the siege of Odawara, whose lord was Toyotomi Hideyoshi (constructed during the siege of Odawara in Tenshō 18 / 1590).
Overview
Ishigakiyama Castle is a siege castle of the late Sengoku period located in Hayakawa, Odawara, Kanagawa Prefecture, built by Toyotomi Hideyoshi in Tenshō 18 (1590) to subjugate the Hōjō clan of Odawara. Also known as Ishigakiyama Ichiyo Castle (literally 'One-Night Castle'), the name derives from an anecdote that upon its completion, the surrounding trees were felled simultaneously to make the castle suddenly appear to those within Odawara Castle, as if it had been constructed overnight.
The siege of Odawara began in March of Tenshō 18, with Hideyoshi mobilizing an enormous force exceeding 200,000 troops to encircle Odawara Castle, the Hōjō clan's stronghold. Meanwhile, Hideyoshi decided to construct a siege castle on the summit of Mount Kasagake (approximately 261 meters above sea level), located about 3 kilometers southwest of Odawara Castle. In the remarkably brief period of only 80 days, he deployed tens of thousands of laborers to complete a fully-fledged stone-fortified castle—a first for the Kantō region. Upon removing the trees surrounding the fortifications upon completion, the castle appeared to suddenly emerge from the landscape, which became the origin of the 'One-Night Castle' legend.
The castle consisted of the main enclosure (honmaru), second enclosure (ninomaru), western bailey (nishi-kuruwa), southern bailey (minami-kuruwa), and northern bailey (kita-kuruwa), with a tenshu platform (tenshu-dai), well bailey (ido-kuruwa), and horse stable bailey (umaya-kuruwa) forming a complete fortress structure. The stonework was primarily constructed using andesite from Sagami Province, employing the nozura-tsumi (rough-hewn dry-stone) stacking technique that, despite its rough construction, demonstrated extraordinary technical prowess for emergency wartime construction. Hideyoshi held tea ceremonies within the castle, inviting prominent daimyo such as Sen no Rikyū, Maeda Toshiie, Tokugawa Ieyasu, and Date Masamune to await the Hōjō clan's surrender.
From within the castle, expansive vistas encompass Sagami Bay, the Izu Peninsula, the Manazuru Peninsula, and the Odawara castle town below, conveying the grandeur of Hideyoshi's unification of Japan. After the Hōjō clan surrendered following a siege lasting over 100 days, Ishigakiyama Castle was abandoned and never subsequently modified; the Sengoku-period stonework has been preserved in nearly its original state to the present day. Today it is maintained as Kanagawa Prefectural Ishigakiyama Ichiyo Castle Historical Park and is counted among Japan's designated National Historic Sites and the Continued List of Japan's 100 Castles.
Connection to Swords
Ishigakiyama Castle symbolizes Toyotomi Hideyoshi's unification of Japan and is directly linked to one of the most crucial turning points in Japanese sword history: the katanagari (sword hunt). In Tenshō 16 (1588), Toyotomi Hideyoshi issued the Katanagari Edict, ordering the confiscation of swords, naginata, bows, firearms, and other weapons from peasants, Buddhist monks, and Shinto priests. This policy was groundbreaking legislation that institutionalized the separation of warrior and farmer classes (heiō bunri) and established the monopoly of sword ownership by the samurai class—a watershed moment in sword history. The construction of Ishigakiyama Castle (1590) came two years later, positioning it within the period of Hideyoshi's power consolidation from the Katanagari Edict through the completion of his unification. Additionally, it is believed that the appreciation and display of celebrated swords (meito) occurred at the tea ceremonies held at Ishigakiyama Castle, alongside tea utensils. Hideyoshi was known as an enthusiastic collector of famous swords, and many meito registered in the Kyōhō Meibutsu Chō (Kyōhō Famous Objects Record) passed into his hands. In particular, the Heshikiri Hasebe—a blade by Hasebe Kunishige, a swordsmith of Yamashiro Province, which Kuroda Josui received from Hideyoshi—is renowned as a famous sword associated with Hideyoshi. At the tea ceremonies and receptions Hideyoshi hosted, the exchange and bestowal of meito occurred repeatedly. The meetings with daimyo at Ishigakiyama Castle should be understood within this context. Furthermore, as a result of the siege of Odawara, the arrangement of daimyo throughout the Kantō and Tōhoku regions was completely reorganized, and Tokugawa Ieyasu's entry into the Kantō was realized (the same year as Odawara's surrender). Considering that this was followed in the Edo period by the systematization of sword authentication and grading culture under the Honjami family of Edo experts, through which sword culture flourished, Ishigakiyama Castle can be seen as symbolizing the 'early modern transformation point' of Japanese sword culture.
Highlights
- Tenshu Platform Stonework — Nozura-tsumi dry-stone fortifications that preserve the legacy of Kantō's first total-stone castle
- Second Enclosure Ruins — Historic site where Hideyoshi held tea ceremonies for assembled daimyo, commanding views of Sagami Bay
- Well Bailey — The castle's water source that sustained the 80-day emergency construction project, with well-preserved stonework
- Observation Point — 360-degree panoramic views of Sagami Bay, Izu Peninsula, Odawara town, and Mount Fuji
- Kanagawa Prefectural Ishigakiyama Ichiyo Castle Historical Park — A designated National Historic Site with maintained walking paths and interpretive signage
- Odawara Castle (approximately 10 minutes by car) — The Hōjō clan's primary castle; historical touring complementary to Ishigakiyama Castle
* Opening hours and admission fees are subject to change. Please check the official website before visiting.