Komoro Castle

Timeline

1. 1487

   Oi Mitsutada raises a hill fort

   Local warlord Oi Mitsutada builds the first fortification here in the late Muromachi period, the seed of Komoro Castle

2. 1554

   Takeda Shingen redraws the plan

   Around Tenbun 23 Takeda Shingen commissions a full rebuild as a regional stronghold for eastern Shinano, traditionally credited to Yamamoto Kansuke

3. 1582

   Three changes of hand in a year

   Takeda is destroyed by Oda-Tokugawa forces in March; the castle passes to Takigawa Kazumasu and then to Yoda Nobushige after the June Honno-ji incident

4. 1590

   Sengoku Hidehisa receives Komoro

   After the Odawara campaign Toyotomi Hideyoshi awards Hidehisa a 50,000-koku Komoro domain; he rebuilds in dressed stone with a three-story keep

5. 1612

   Otemon Gate built

   The surviving five-bay yagura-mon Otemon Gate is raised in Keicho 17, with irimoya roof and clay tile cladding — later a national Important Cultural Property

6. 1622

   Sengoku transferred to Ueda

   Sengoku Tadamasa is moved to Ueda Castle in Genna 8; Komoro cycles through Matsudaira, Aoyama, and Sakai daimyo over the next 80 years

7. 1626

   Donjon destroyed by lightning

   In June Kanei 3 lightning sets fire to the three-story keep with its gold-leaf paulownia-crest tiles; it is never rebuilt

8. 1702

   Makino family takes Komoro

   Makino Yasushige is enfeoffed in Genroku 15; his line holds Komoro Domain for ten generations until the Meiji Restoration

9. 1742

   Inu-no-manmizu flood

   A catastrophic flood damages the Otemon, Ashigara-mon, and San-no-mon; San-no-mon will later be rebuilt in 1766 in a different yagura-mon style

10. 1873

    Castle abolition order

    Komoro Castle is abolished under the Meiji haijo-rei; most structures are demolished or relocated to nearby temples and private houses

11. 1880

    Kaikoen opens

    Former Komoro samurai pool funds to buy the inner bailey grounds at auction and reopen the site to the public as Kaikoen park

12. 1926

    Honda Seiroku redesigns the park

    Forest scientist Honda Seiroku redesigns Kaikoen in Taisho 15, expanding it as a modern landscape park integrating castle ruins and native scenery

13. 2004-2008

    Otemon full restoration

    A four-year dismantle-and-reassemble project peels away later restaurant-era alterations and returns the Otemon to its early Edo silhouette

14. 2006

    Listed among the 100 Fine Castles

    On April 6 Heisei 18 Komoro Castle is added as number 28 on the official 100 Fine Castles of Japan list by the Japan Castle Foundation

Detailed History

Komoro Castle began in 1487 (Chokyo 1, late Muromachi period) as a hill fort raised by Oi Mitsutada, a local warlord of the Shinano Saku district. In the mid-16th century, as Takeda Shingen consolidated his hold over eastern Shinano, he commissioned a comprehensive rebuild around 1554 (Tenbun 23). Local tradition credits Shingen's master strategist Yamamoto Kansuke with the new layout, although no contemporary documents confirm this attribution. The resulting plan still defines the footprint of the ruins today. Under Takeda Katsuyori the castle was commanded by Shimosone Joki, a kinsman of the Takeda. In March 1582 the Oda-Tokugawa invasion of Kai threw the eastern Takeda lands into chaos: Joki cut down the refugee Takeda Nobutoyo, presented his head to Oda Nobunaga, and was himself executed shortly afterward. With the Takeda destroyed, Komoro passed to Takigawa Kazumasu, Nobunaga's general. The Honno-ji incident on June 2, 1582 unraveled this arrangement. Takigawa was beaten at the Kannagawa by the Later Hojo, fell back to Komoro on June 21, and withdrew to Ise Nagashima. The castle then changed hands to Yoda Nobushige and eventually to Tokugawa Ieyasu. After the 1590 Odawara campaign Tokugawa Ieyasu assigned Komoro to his general Sengoku Hidehisa as a 50,000-koku daimyo holding, later confirmed under the Tokugawa shogunate. Hidehisa rebuilt the castle in dressed stone, raised the bailey walls, and crowned the central keep with a three-story donjon roofed in gold-leaf tiles bearing the paulownia crest. His son Tadamasa was transferred to Ueda in 1622 (Genna 8). In June 1626 (Kanei 3) lightning destroyed the donjon, which was never rebuilt. During the Edo period Komoro Domain cycled through the Matsudaira, Aoyama, and Sakai houses before the Makino family took possession in 1702 (Genroku 15) and held it until the Meiji Restoration. The 1742 (Kanpo 2) Inu-no-manmizu flood badly damaged the Otemon and San-no-mon; the latter was rebuilt in 1765. The 1871 abolition of the han system led to most structures being demolished or moved. In 1880 former Komoro retainers purchased the inner bailey land and opened it as Kaikoen, expanded under landscape architect Honda Seiroku in 1926. The Otemon underwent full restoration in 2004-2008, and in 2006 the castle was added to the official 100 Fine Castles of Japan list as number 28.

Cultural Significance

Komoro Castle's documented value rests above all on its two surviving wooden gates, both nationally designated Important Cultural Properties. The Otemon, completed in 1612, is a five-bay yagura-mon with an irimoya roof and original tile cladding — a rare early Edo castle gate that has stayed on its original site. The San-no-mon was rebuilt in 1765 after the 1742 flood, as a three-bay yagura-mon with a hipped roof and pan tiles, owned by the adjacent Kaiko Shrine. The nicknames map the castle's character. Suigetsu-jo (Drunken Moon), Hakkaku-jo (White Crane), Nabefuta-jo (Pot-lid), and most famously Ana-jo (Buried Castle) converge on one fact: the baileys sit below the level of the surrounding town, an inversion almost unknown elsewhere in Japan. Strategists exploited the deep ravines of Mount Asama's lahar flows on the east and the cliffs of the Chikuma River on the west as natural dry moats. Modern Kaikoen began in 1880 when former Komoro samurai pooled funds to buy the inner grounds at auction; forest scientist Honda Seiroku redesigned the park in 1926. The San-no-mon appears in the title sequence of Fuji TV's Sazae-san anime, embedding Komoro in postwar visual culture as small-town Japan shorthand. The site is also a literary pilgrimage: Shimazaki Toson's Chikumagawa stele and Wakayama Bokusui's tanka on the ninomaru walls anchor a small canon of modern Japanese verse.

Architectural Details

The plan comprises five baileys — honmaru, ninomaru, kita-no-maru, minami-no-maru, and san-no-maru — laid out lower than the surrounding castle town, the defining Ana-jo configuration. The system maximized natural defenses by adopting the ravines of Mount Asama's lahar terraces on the east and the cliffs over the Chikuma River on the west as ready-made dry moats, reducing artificial earthworks to a minimum. In its Edo prime the castle had six main gates: Otemon, Ni-no-mon, San-no-mon, Nakajikiri-mon, Kuromon, and Akazu-mon. The first four were all watari-yagura-mon (turret-bridge gates), and Nakajikiri-mon was an unusually large three-story turret gate. The keep was a three-story bogata (watchtower-style) donjon roofed in gold-leaf clay tiles stamped with the paulownia crest — a status statement on the eastern Shinano landscape. A technical highlight is the mizu-yagura on the ninomaru, a water tower that diverted Nakazawa River flow onto the bailey. Reliable water was a chronic problem for highland castles and this fix appears in few other surviving plans. Stone walls are predominantly nozura-zumi (rough-stack) from the Sengoku reorganization. Surviving above-ground elements are the Otemon, the San-no-mon, the tenshudai foundation, and bailey walls; the Kuromon now serves as the gate of Shogenin temple and the Ashigara-mon as that of Kogaku-ji temple.