Born in 1554 in Azai District, Omi Province (present-day Nagahama, Shiga Prefecture). He first served Azai Nagamasa, but after the Azai clan's fall in 1573 joined the Oda camp as a subordinate of Akechi Mitsuhide. At the Battle of Shizugatake in 1583 he distinguished himself alongside Fukushima Masanori and Kato Kiyomasa, earning a place among the "Seven Spears of Shizugatake" and a grant of 3,000 koku in Yamashiro Province. In 1585, following Hideyoshi's conquest of Shikoku, he was made daimyo of Sumoto in Awaji Province with 30,000 koku, and drawing on experience gained during the Korean campaigns (1592-98) he carried out a major reconstruction of Sumoto Castle into an early-modern stone fortress and naval base. The "climbing stone walls" (noborishigaki) built at this time survive today as one of only a handful of such examples nationwide. After 24 years as lord of Sumoto, he initially fought for the Western army at the Battle of Sekigahara in 1600, but switched to the Eastern army mid-battle when Kobayakawa Hideaki defected, and his domain was subsequently confirmed. In 1609 he was transferred with an increased stipend to Ozu in Iyo Province. He took Buddhist vows in 1617 under the name Rinshoin and died in Kyoto in 1626 at the age of 73.

A warrior brave enough to be counted among the Seven Spears of Shizugatake, yet also shrewd enough to read the tide of battle and switch to the Eastern army at Sekigahara. He also possessed the technical insight to apply his naval experience to castle stonework.

The climbing stone walls of Sumoto Castle, built by Wakisaka Yasuharu drawing on his Korean campaign experience, are a rare surviving structure nationwide and were a key factor in the castle's selection as one of the Continued 100 Fine Castles of Japan in 2017. The stonework still visible today reflects Sumoto Castle's role as the base of the Awaji naval forces.