The origins of Iwadono Castle are mostly unknown. There is much debate whether it was a Takeda castle or Oyamada castle, but the Oyamada theory seems to fit best. Regardless, since the Oyamada were vassals of the Takeda, Iwadono Castle played a critical role in defending the entrance to Takeda's Kai domain. It guarded the roads in the valley and served as an important smoke signaling station.
In 1582, Takeda Katsuyori, escaping from Nobunaga's forces, sought refuge at this castle but was denied entry by Oyamada, essentially making Katsuyori's flight hopeless. Oyamada was later executed by the Oda, ostensibly for betraying his lord and being un-samurai-like. The castle was essentially abandoned at this time, but may have been maintained in the early Edo Period as part of the escape route to Kofu if the Tokugawa ever needed to flee Edo.
Mt. Iwadono has suffered a lot of damage from typhoons, heavy rains, and rock slides the past few years. I had been waiting for a good cold winter day to visit for a couple years but the main trails had been closed for some time. I finally got my chance in January 2019 for my first castle visit of the new year. The castle remains are very interesting and unique in how they use natural boulders and also cut into the cliff face to create gates and defenses. There are also stunning views of Mt. Fuji along the way and from the top of the mountain. Enjoying such a great view every day, the Oyamada may have had an over-inflated ego or sense of their own power.
As of May 2020, all accessible routes to the top of the mountain are closed again. Due to a rock slide, the trails have been closed since August 2019 again. There are other long and difficult mountaineering trails from other directions that will take you to the top but they are only recommended for at least intermediate level mountain climbers (not just intermediate level hikers) including areas with chains and ladders to scale the boulders. If you are interested in visiting, check the website or contact the Otsuki Tourism Association for the current conditions before planning your trip.
The Fureai-no-yakata (yagura looking building) near the base of the mountain is open every day except Mondays. It has a nice view of Mt. Fuji and displays photos from local photographers. They also have maps of the castle and information about the hiking trails, but the trails from here to the top of the mountain and castle ruins are currently closed.
|English Name||Iwadono Castle|
|Castle Condition||No main keep but other buildings|
|Designations||Top 100 Mountaintop Castles, Prefectural Historic Site|
|Historical Period||Pre Edo Period|
|Access||Otsuki Sta (JR Chuo Line, Fujikyuko); 15 min walk to the trail head, 45 more mins to the top|
|Visitor Information||mountain, open 24/7|
|Time Required||150 mins|
|Location||Otsuki, Yamanashi Prefecture|
|Coordinates||35° 37' 17.72" N, 138° 56' 59.64" E|
|Added to Jcastle||2011|
|Admin Year Visited||2019|
|Admin Visits||January 14, 2019|