Lifespan: Eiroku 11 (1568) to Kanei 14 (1637)
Other Names: Hachirō (childhood), Muneoki
Lord: Ōtomo Yoshimune
Father: Wakabayashi Shigeoki
Siblings: Munemasa, Heiemon, Hanemon, Munemasa (with different characters)
Wakabayashi Munemasa served as a bushō during the Azuchi-Momoyama and early Edo periods. He was a commander of naval forces comprised of retainers of the Ōtomo clan of Bungo Province in northern Kyūshū.
Munemasa was born as the eldest son and designated heir of Wakabayashi Shigeoki, a retainer of the Ōtomo clan.
Originally, the Wakabayashi clan were a gōzoku, or wealthy family, from Shimotsuke Province but, began to serve the Ōtomo clan prior to the Muromachi period. The clan possessed landholdings in Isshakuya in the township of Saga-no-seki in Bungo. Owing in part to their location, the Wakabayashi served in the core of the naval forces of the Ōtomo clan.
In 1578, during his coming-of-age ceremony, he received one of the characters from the name of his lord, Ōtomo Yoshimune, and adopted the name of Munemasa. In 1586, after the Shimazu army marched north from their home in Satsuma Province to invade Bungo, Munemasa joined in the defense at the Maruo fortress located on a hill near the coastline in Isshakuya which served as the base for the Wakabayashi clan.
In 1593, during the Bunroku Campaign, his lord, Yoshimune, was accused of fleeing in the face of an attack by the Ming forces from China. After returning from the war, upon orders from Toyotomi Hideyoshi, Yoshimune was removed from his position and turned-over to the custody of the Mōri clan. While Yoshimune was relegated to confinement in Suō Province, Munemasa accompanied him.
Later, Munemasa left the Ōtomo family and served Matsudaira Sadakatsu for a fief of 200 koku. In his latter years, Munemasa resided in Nagasaki in Hizen Province in western Kyūshū, dying there in 1637.
Munemasa was known as an intrepid warrior, skilled at the bow with a heavy draw weight and possessing full mastery of the sword from the Yagyū school of swordsmanship.