Kōsaka Masanobu

Kōsaka Masanobu
Kōsaka Masanobu's portrait in The Twenty-four Generals of Takeda Shingen (Japanese Woodblock Print) made by Yoshikazu in 1582
Native name	高坂 昌信
Born	1527
Died	June 12, 1578 (Aged 51)

Kōsaka Masanobu (高坂 昌信^?) also known as Kasuga Toratsuna (春日 虎綱^?, 1527 – June 12, 1578) was a Japanese samurai warrior of the Sengoku period. He was known as one of his "Twenty-Four Generals of Takeda Shingen". He is often credited as the original author of Kōyō Gunkan, which records the history of the Takeda family and their military tactics. However, recent studies strongly suggest that other writers used Kōsaka's name to boost the book's credibility.

The association between Masanobu and Shingen began in 1543 as a love relationship. At the time they were 16 and 22, respectively. Such relationships were in vogue in pre-modern Japan, a tradition known as shudo. The love pact signed by the two, in University of Tokyo's Historical Archive, documents Shingen's pledge that he was not in, nor had any intentions of entering into, a sexual relationship with a certain other retainer, and asserts that "since I want to be intimate with you" he will in no way harm the boy, and calls upon the gods to be his guarantors. (Leupp, pp. 53–54)

Kōsaka is known as one of the three Danjō that served the Takeda family, along with Sanada Yukitaka and Hoshina Masatoshi (Danjō stands for a formal title, Danjōchū; 弾正忠). Among these three, Kōsaka was known as the "Nige Danjō" (逃げ弾正; literally, the fleeing Danjō), because of his cautious commanding and skillful retreats.