Masahiro was the son of Ôuchi Norihiro and was at first known as Taro. He fought in Kyoto during the Ônin War in support of the Yamana. He afterwards returned to the Western provinces and expanded and consolidated the Ôuchi influence there. He took advantage of the political situation to increase the Ôuchi's domination of trade with China.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005