Yamana Sozen

Yamana Sozen became a Buddhist monk and took the name Sozen, though he remained politically and militarily active. His nickname 'Red Monk' (Aka Nyudo) came from his red monk's robes and his warlike nature.

Sozen led military campaigns that expanded Yamana control to 11 provinces, making him one of the most powerful daimyo in Japan. His aggressive expansion alarmed other clans, particularly the Hosokawa.

Sozen's rivalry with Hosokawa Katsumoto intensified over control of the shogunate. The two kanrei clashed over succession and policy, with Sozen supporting Shogun Yoshimasa's son while Katsumoto backed his brother.

Sozen commanded the Western Army (Seigun) in the Onin War, opposing Katsumoto's Eastern Army. His forces fought fierce battles in Kyoto, burning temples and palaces, and the war spread chaos across Japan.

Sozen died of illness in 1473, the same year as his rival Katsumoto. His death did not end the Onin War, which continued until 1477, but it removed one of the key instigators of the conflict.