Masugata Castle (枡形城 Masugata-jō) is located in Tama Ward, Kawasaki, Kanagawa Prefecture.
The castle was constructed on a hill facing the southern banks of Tama River.
(This map is based on Tokyo Terrain Map powered by gridscapes.net )
The castle site formed a formidable stronghold, surrounded by cliffs about 60 meters above the river.
It was Inage Saburō Shigenari (稲毛三郎重成), son of Oyamada Arishige (小山田有重), who was said to have built the first fortification on the site in the early days of the Kamakura shogunate. In 1504, the castle saw action when Hōjō Sōun (北條早雲, 1432-1519, also known as Ise Shinkurō, pitched camp there for three days during his campaign against Yamanouchi Akasada of the Uesugi clan. Sōun and Imagawa Ujichika supported the Uesugi branch family of Ōgigayatsu Tomoyoshi and defeated the enemy in the Battle of Tachigawara (modern-day Tachikawa). Masugata Castle was reinforced in 1569, when the Takeda, a former ally of the Hōjō, turned against them and attacked the Hōjō headquarters at Odawara Castle. At the end of the Sengoku Period, the castle was abandoned and subsequently fell into ruin.
Nowadays, the castle ruins are located within the perimeter of Ikuta Green Park (生田緑地 Ikuta Ryukuchi) .
A ten-minute walk from Mukogaoka-Yuen Station, I had to climb a forested slope and reached the castle site on top of the hill another ten minutes later.
Surrounded by some open space, there was a castle monument, a restored castle gate (see the picture on top) and a wooden fence.
From the observatory, Tokyo is well visible in the distance beyond the Tama River.
An array of castles built in the hills south of Tama River constituted the northern line of defence for Kamakura.
（Date of visit: 26th May 2013）