The Shingen Museum, with support from the Agency for Cultural Affairs, held a special countdown exhibition in 2022, “The Renowned Lord Takeda Shingen and his Legendary General Yamamoto Kansuke,” to commemorate the 450th anniversary of Shingen's death.

“The Legend and Truth of Yamamoto Kansuke,” introduced the real Yamamoto Kansuke, the most famous of the Takeda clan’s vassals, from the legendary military strategist mentioned in the Kōyō Gunkan, a record of the military exploits of the Takeda clan, to the real Yamamoto Kansuke as revealed in contemporaneous documents.

In 1541, Takeda Shingen, supported by his vassals and fiefdom, banished his tyrannical father Nobutora to Suruga Province, modern-day Shizuoka Prefecture, and became the head of the Takeda clan, stabilizing the region and launching a full-scale invasion of neighboring Shinano Province, modern-day Nagano Prefecture. It was near the beginning of this expansion of the Takeda clan’s power that Yamamoto Kansuke entered into the service of Shingen (1543 or 1544).

Yamamoto Kansuke was recommended to Shingen as a man with excellent castle-building skills, and was promptly taken into Shingen’s service. Yamamoto is said to have successfully employed the pincer movement during the 4th Battle of Kawanakajima, in which he fought a fierce battle with Uesugi Kenshin. However, other than the description of Yamamoto in the Kōyō Gunkan, there were no other historical documents that indicated the existence or activities of the legendary general until his name was confirmed in an ancient document discovered in 1969.

The document revealed that Yamamoto was dispatched as an important messenger to keep the Ichikawa clan, a powerful military clan in northern Shinano Province, in the Takeda army. Another ancient document discovered in Gunma Prefecture in 2008 contains evidence of Yamamoto’s true significance as one of Shingen’s most trusted generals. This document revealed that Shingen had requested Yamamoto to consider military operations in northern Shinano and even to visit Shingen’s chief vassal when the vassal was ill.

The exhibition included old documents and paintings depicting Yamamoto, who died in the 4th Battle of Kawanakajima in 1561. The exhibition revealed the real-life Yamamoto Kansuke, who worked tirelessly for Shingen, and brought to light the life of a legendary general from the Warring States period.