In 1337, he responded to a call-to-arms from Ashikaga Tadayoshi, traveling to Yamato province, and later leading Shimazu forces against the Southern Court at Hyôgo-no-tsu and Minatogawa. He died on 1340/1/24 as a result of injuries from falling from his horse, at age 19. Following the death of their father in 1363, the headship of the Shimazu clan was then split between Munehisa's younger brothers, Shimazu Morohisa and Ujihisa.
He is buried at the Shimazu clan cemetery at Fukushô-ji in Kagoshima alongside his brothers. As the temple was not founded until the end of the 14th century, the graves of Munehisa and his brothers are the oldest in the cemetery.
- "Shimazu Munehisa," Nihon jinmei daijiten, Kodansha 2009.