Yasuharu entered the service of Akechi Mitsuhide and fought for him in Tamba province (1576-77) at Kuroi and at Yamazaki (1582). He afterwards joined Toyotomi Hideyoshi and distinguished himself at Shizugatake, being named one of the 'Seven Spears' of that battle. He received the fief of Awaji Island in 1585 and became known as a naval commander, directing ships during the Kyushu and Odawara Campaigns. He was one of Hideyoshi's primary naval commanders in the Korean Campaigns but was heavily defeated by the Korean Admiral Yi Sun Shin at the Battle of Hasendo (1592). He led almost 1,000 men to the Battle of Sekigahara as part of the western army, though just beforehand he decided to actually join Tokugawa Ieyasu. He was postioned with Kobayakawa Hideaki and joined him in betraying Ishida Mitsunari and the western cause. He was afterwards given a fief in Iyo province worth some 50,000 koku, from which he was moved 1617 to Iida in Shinano province. Yasuharu was also known as Wakizaka Jinnai and came to hold the rank of Nakatsukasa-shosuke. He was noted for the silver pelt he carried - given to him by Hatano retainer Akai Naomasa before the latter committed suicide in 1576.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005