Nagurumi castle is located on a bluff on the west bank of the Tone River, about four km north of Numata castle. It was near two of the three highways between the Kantô plain and Echigo province, the Mikuni highway and the Shimizu highway.
The Tone District is surrounded to the south by Mt. Akagi, to the north by the Tanigawa Range as well as by mountains on the east and west. From the Kamakura Period to the Sengoku Period it was ruled by the Numata clan . At their height they had family members and retainers such as the Nagurumi, Ogawa, Ishikura, Kawada placed in strategic positions throughout the district. However, they lost control of the area during the Tenbun period (1532-1555) when the Hôjô of Odawara, who were taking over the Kantô, passed Mt. Akagi, and took control of the area. In 1560, Uesugi Kenshin of Echigo crossed the Tanigawa Range via Mikuni Pass and attacked Nagurumi Castle and other fortifications in the area. He took possession of Numata Castle and used it as a base to fight the Hôjô in Maebashi and Musashi province. However, during the strife in Echigo after his death in 1578 the Hôjô attacked Numata and gained control again.
Meanwhile, from 1579-1580, Sanada Masayuki of the Ueda area of Shinano province by the order of Takeda Katsuyori started taking control of the valley of the Azuma River, which rises just over Torii Pass east of Sanada Village and enters the Tone River south of Numata. He took Iwahitsu岩櫃 Castle (near Nakanojô in the Azuma Valley) and then fortifications in the Tone region, including Nagurumi Castle, and finally his goal of Numata. From then on, there was continual fighting between the Sanada and Hôjô concerning Numata. (Tokugawa Ieyasu's attack on Ueda in 1585 was in support of the Hôjô in this quarrel.)
When Toyotomi Hideyoshi consolidated his control of central Japan, he urged the Hôjô to visit the capital, but as a condition of their trip the Hôjô demanded that they be given the two districts of Tone and Azuma which were held by the Sanada. In response to Hideyoshi, Masayuki replied that he was willing to give up Numata, but would not give up Nagurumi. Finally in the seventh month of 1589, a settlement was reached by which the Hôjô would be given the east bank of the Tone (including Numata) and the north bank of the Akatani River, which flows into the Tone north of Nagurumi, while the Sanada would get the rest of the west bank, including Nagurumi and the Azuma district, and in addition Minowa in the Ina district of southern Shinano province as a replacement for Numata. However, in the eleventh month the Hôjô commander in Numata, Inomata Kuninori 猪俣 邦憲, attacked and took Nagurumi castle. Hideyoshi was incensed, and immediately announced an attack on Odawara. The 7th month of the next year (1590) Odawara fell, and Hideyoshi ruled all Japan. Numata was given to the Sanada, and Nagurumi castle was abandoned.
Excavations have found the remains of an old residence in the Hannya Enclosure (Kuruwa) 般若郭, presumably that of the Nagurumi family. Most of the present fortifications were built by Sanada Masayuki. Earthworks (土塁) over two meters high were build around each enclosure. This was built as a base from which to attack Numata Castle.
- Explanation sign on site
- Sanada Family Materials
- Map of location of Nagurumi castle, in Gunma prefecture, Tone district 利根郡 Minakami town みなかみ町 Tsukiyono 月夜野, on Rt. 17 just west of the Tsukiyono Ôhashi bridge