The siege of Nagakubo (長窪城) was a battle of Japan's Sengoku period. It took place in 1543 as part of Takeda Shingen's bid to control Shinano Province, Japan. He took the castle of his former ally, Oi Sadataka, who had deserted him to ally with Murakami Yoshikiyo. Sadataka was sent to Shingen's home city of Kōfu as a prisoner, where he was then killed.
References Turnbull, Stephen (1998). 'The Samurai Sourcebook'. London: Cassell & Co.