Yamamoto Kansuke was a Japanese samurai of the Sengoku period. He was known as one of the "Twenty-Four Generals of Takeda Shingen". Also known by his formal name, Haruyuki (晴幸). He was a brilliant strategist, and is particularly known for his plan which led to success in the fourth battle of Kawanakajima against Uesugi Kenshin. However, Kansuke never lived to see his plan succeed; thinking it to have failed, he charged headlong into the enemy ranks, dying in battle.

The Battles of Kawanakajima were a series of battles fought in the Sengoku period of Japan between Takeda Shingen of Kai Province and Uesugi Kenshin of Echigo Province from 1553 to 1564. Shingen and Kenshin contested each other for control of the plain of Kawanakajima between the Sai River and Chikuma River in northern Shinano Province, located in the present-day city of Nagano. The battles were triggered after Shingen conquered Shinano, expelling Ogasawara Nagatoki and Murakami Yoshikiyo, who subsequently turned to Kenshin for help.