Lifespan: Eiroku 8 (1565) to 12/12 of Tenshō 14 (1587)
Lord: Ōtomo Yoshishige → Ōtomo Yoshimune
Father: Bekki Shigetsura (under another account he was adopted from the Usuki clan)
Mother: From the Shiga clan
Siblings: Munetsune, Munetoshi
Wife: Daughter of Yoshihiro Akinobu
Children: Senju, Nobutsune, daughter (wife of Bekki Masayuki; later wife of Yamaga Koshiemon), Yoshihiro Yahei
Bekki Munetsune served as a bushō and retainer of the Ōtomo clan of Bungo Province during the Azuchi-Momoyama period. Munetsune further served as the seventeenth head of the Bekki clan, a branch of the Ōtomo, and lord of Yorigatake Castle.
Munetsune was the eldest son of Bekki Shigetsura. Munetsune originally received for his name one character each from his father, Shigetsura, and his lord, Ōtomo Yoshimune, yielding the name of Munetsura. Shigetsura, however, was displeased with the important roles given to another retainer of the Ōtomo named Tawara Chikakata. Shigetsura protested to accusations that he had colluded with the Shimazu clan, but Yoshimune refused to listen, and expelled him to Fujikita Castle. In 1586, Shigetsura was either executed upon orders of Yoshimune or else compelled to kill himself.
Following the death of his father, Munetsune inherited the clan. Munetsune was determined to restore his family name by fighting against the Shimazu. In 1587, the Shimazu laid siege to Tsuruga Castle, defended by Toshimitsu Sōgyo. Munetsune sought to provide reinforcements to Sōgyo. The Shiga clan (the wife of Shigetsura and mother of Munetsune) also carried a burden owing to her husband’s alleged betrayal. Upon Munetsune’s deployment, the Shiga slayed his younger brothers, causing Munetsune to act with utter determination. After burning ancestral writings and family treasures, he sent his eldest son, Nobutsune, to Tachibanayama Castle, and his wife and daughter to Kakei Castle, took care of personal affairs and deployed. After sending him along, his mother promptly took her own life.
Early in 1588, Munetsune participated in the Battle of Hetsugigawa. Munetsune joined Sengoku Hidemasa and Chōsokabe Motochika in battle against the Shimazu (led by Niiro Daizen). Munetsune prevailed as the forces clashed four or five times, but, in the end, over 100 members of the clan including Bekki Shigetoki, Bekki Munemasa, and Bekki Shigenao perished.
Prior to his deployment, Munetsune left his eldest son (Nobutsune) in Fujikita Castle to protect the Bekki clan. His younger brother, Munetoshi, survived as a hostage of the Shimazu. After the Kyūshū heitei, a campaign from 1586 to 1587 led by the forces of Toyotomi Hideyoshi to subjugate Kyūshū, the Shimazu released Munetoshi, who joined other members of the clan to serve a relative named Tachibana Muneshige. Munetoshi later received one of the characters from Muneshige and changed his name to Shigeteru. He accompanied Muneshige to the territory of Tanagura. In the Edo period, the lineage of the Bekki clan continued under the Yanagawa han of Chikugo Province, while Nobutsune inherited the remnants of the clan.