Masanori was a son of Akamatsu Masamoto and a cousin of Akamatsu Yoshisuke. He had a reputation as a discerning and proud general. He held Kôzuki castle in Harima province and came under attack by the Oda (as led by Toyotomi Hideyoshi) in late 1577. Masanori resisted stoutly but when a relief force sent by the Ukita was defeated and Kôzuki isolated, the Oda army launched an all-out attack. Masanori killed his family before committing suicide and thus died along with some 1,100 of his men.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005