Some local legends say a castle existed here as early as the Kamakura Period, but there has never been an excavation to determine if a fortification may have existed here during that time period or not. The castle ruins you see today are obviously from the mid 1500's. It was most likely built by Takeda Shingen in his battles with the Annaka at nearby Matsuida Castle (6 km away) or Annaka Castle (2.5 km away). It may have also been built as a satellite fortification by the Hojo, but the Takeda theory seems to make the most sense.
The castle is remarkably well preserved. Given the location on a fairly small mountain I wouldn't have been surprised if it had been developed over for some nice housing with a view or other public facility. The main approach to the honmaru is well maintained with signs pointing out the main features, which are mostly small baileys and trenches. What's really interesting about this site is if you try to walk those trenches all around the castle. You can see their size and the layout of the castle much better that way.
|English Name||Isobe Castle|
|Founder||Takeda Shingen (?)|
|Year Founded||mid 1500's|
|Castle Condition||Ruins only|
|Designations||Local Historic Site|
|Historical Period||Pre Edo Period|
|Access||Isobe Sta (Shin'etsu line), 15 min walk|
|Visitor Information||Park, open any time|
|Time Required||45 mins|
|Location||Annaka, Gunma Prefecture|
|Coordinates||36° 17' 52.40" N, 138° 51' 39.78" E|
|Added to Jcastle||2018|
|Admin Year Visited||2018|
|Admin Visits||March 11, 2018|