Hosokawa Katsumoto in the context of "Kanrei"

The Ōnin War (応仁の乱, Ōnin no Ran), also known as the Upheaval of Ōnin and Ōnin-Bunmei war, was a civil war that lasted from 1467 to 1477, during the Muromachi period in Japan. Ōnin refers to the Japanese era during which the war started; the war ended during the Bunmei era. A dispute between a high official, Hosokawa Katsumoto, and a regional lord, Yamana Sōzen, escalated into a nationwide civil war involving the Ashikaga shogunate and a number of daimyō (大名, feudal lords) in many regions of Japan.

The war initiated the Sengoku period, "the Warring States period." This period was a long, drawn-out struggle for domination by individual daimyō, resulting in a mass power-struggle between the various houses to dominate the whole of Japan.

Yamana Sōzen (山名 宗全; July 6, 1404 – April 15, 1473) was originally Yamana Mochitoyo (山名 持豊) before becoming a monk. Due to his red complexion, he was sometimes known as Aka-nyūdō, "the Red Monk". He was one of the shogun daimyōs who fought against Hosokawa Katsumoto during the Ōnin War in Heian-kyō.