Yamana Sōzen , was originally before becoming a monk . Due to his red complexion , he was sometimes known as " Aka - nyūdō " , ' the Red Monk ' . He was one of the " daimyo " who fought against Hosokawa Katsumoto during the Ōnin War in Kyoto . Yamana Sōzen was born to Yamana Tokihiro ( 1367 – 1435 ) , head of the Yamana clan . Tokihiro was the " shugo " governor of Tajima , Bingo , Aki , and Iga provinces . Tokihiro , who was often in bad health , retired in 1433 and passed his numerous lands to Sōzen . Sōzen went on to defeat Akamatsu Mitsuhide ( 1373 & ndash 1441 ) in the Kakitsu Incident , and became governor Harima Province the same year . The Yamana clan had seen many defeats over the years , while the Hosokawa clan was one of the three families which controlled the position of " kanrei " , deputy to the Shogun . Thus , Yamana Sōzen resented the wealth and power enjoyed by his son - in - law , Hosokawa Katsumoto . Unwilling to engage him in open warfare until he was sure of his strength , Yamana chose to intervene in a number of succession disputes and other political affairs , thwarting Hosokawa ' s plans and desires , and slowly gaining allies for himself . In 1464 , a succession dispute erupted over the shogunate itself . The Shogun , Ashikaga Yoshimasa , was considering retiring . Hosokawa supported the Shogun ' s brother , Ashikaga Yoshimi as the successor , and so Yamana chose to support Ashikaga Yoshihisa , the Shogun ' s infant son . In 1466 , both sides having spent several years gathering forces , both Yamana and Hosokawa felt ready to engage the other , and skirmishes began to break out . In 1467 , the first year of Ōnin by Japanese reckoning , both men began to prepare more seriously for the coming conflict ; they sought safehouses and planned for fighting in the streets . Yamana took Yoshimi to the Shogun ' s residence , where Hosokawa , who supported Yoshimi ' s claim to the shogunate , could not get at him . He was essentially a hostage . Seeing that open war in the capital would spread to the provinces , the Shogun declared that the first to make an attack within the city would be labeled a rebel against the Shogunate , and enemy of the state . Thus , for several months , the conflict quieted , neither side willing to make a move . Finally , in March 1467 , the home of a Hosokawa officer was destroyed by fire . After several more minor attacks and political maneuvers , in May , Hosokawa attacked outright the mansion of one of Yamana ' s generals . Nevertheless , Yamana , not Hosokawa , was labeled a rebel , and enemy of the state . Some of Yamana ' s followers deserted , joining Hosokawa ' s morally superior side , but many more switched sides as a result of the work of Hosokawa ' s emissaries to the provinces where Yamana and his allies drew their armies . By New Year ' s of 1468 , nearly a year since the war began , the fighting tapered off . For much of that year , the two forces engaged in glaring contests and limited sorties , both desiring to rebuild and to act only defensively . Both spent the next several years in political , not military , conflict , and in 1469 , the Shogun named Yoshihisa , his son , to be his heir . But Hosokawa was weary of battle , and wished for peace . Peace was had , and a few years later , in 1473 , both Hosokawa and Yamana died .