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In 1582, as Takeda Katsuyori was feeling the pressure from Tokugawa and Oda forces invading his lands, Sanada Masayuki invited him to move to one of his strongest fortresses, Iwabitsu Castle. Sanada laid the foundation for a fortified home at the Karamete Entrance to Iwabitsu Castle. If you visit the site, you'll see that it's tucked away in a somewhat hidden valley and would have been a defensible and well fortified place for Katsuyori. Unfortunately, Katsuyori fell into a trap by one of his vassals, Oyamada Nobushige who was in league with the Oda. Oyamada convinced Katsuyori to come to Iwadono Castle in the Takeda homeland of Kai rather than fleeing Kai completely and moving into the Sanada lands in Kozuke. When Katsuyori arrived, the castle was barred and he was not allowed in. He fled Iwadono and eventually committed suicide at Mt. Tenmoku while being pursued by Takigawa Kazumasa, an Oda vassal. Even though Oyamada had joined with the Oda, Oda had him executed for his dirty betrayal of Katsuyori.

Visit Notes

Seiryuin is best visited in a trip to Iwabitsu Castle. Start from Gobara Station and walk to Seiryuin and then walk the "Sanada Road" to Iwabitsu Castle. Gunma Haramachi is often given as the closest train station to Iwabitsu Castle but it is a long boring uphill walk. This route is much better and mostly wooded. After Iwabitsu Castle you can walk downhill all the way to Gunma Haramachi for the return trip.

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  • Foundation of Katsuyori's palace
  • Gobara Station and Mt. Iwabitsu
  • Palace foundation
  • Palace foundation
  • Palace foundation and Mt. Iwabitsu
  • Palace foundation
  • Palace foundation
  • Palace grounds
  • Distant view of the mountain
  • Old building and wall
  • Map
  • Map

Castle Profile
English Name Seiryuin
Japanese Name 潜龍院
Founder Sanada Masayuki
Year Founded 1582
Castle Type Hilltop
Castle Condition Ruins only
Historical Period Pre Edo Period
Features trenches, stone walls
Visitor Information
Access Gobara Sta. (Agatsuma Line), 25 min walk
Visitor Information mountain trials, be open any time.
Time Required 20 mins
Location Higashiazuma, Gunma Prefecture
Coordinates 36° 33' 14.72" N, 138° 47' 49.52" E
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Added to Jcastle 2016
Admin Year Visited 2016
Admin Visits April 29, 2016

(3 votes)
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25 months ago
Score 1++
Say, did you ever come across why they call it 潜龍院? Was there a temple there before they built the yakata? It was also called Furuya-yakata (古谷館).


25 months ago
Score 0++
Since Katsuyori never showed up some monk (?) built a little temple or used the structure as a temple.


25 months ago
Score 0++
So it was after. Got it. Bit weird that but I suppose the more important issue than the name is when the stone wall is from.