Lifespan: Tenbun 6 (1537) to 6/4 of Tenshō 10 (1582)
Rank: bushō, lord of Bitchū-Takamatsu Castle
Lord: Ishikawa Hisatake → Mōri Terumoto
Father: Shimizu Munenori
Siblings: Munetomo, Muneharu, Nanba Munetada
Wife: Daughter of Ishikawa Hisataka
Children: Muneyuki, Kageharu, Nanba Munesada, daughter (wife of Nakashima Motoyuki) daughter (wife of Komagine Seiemon)
Shimizu Muneharu served as a bushō during the Sengoku period. Muneharu served the Mimura and Mōri clans, and was the lord of Bitchū-Takamatsu Castle.
In 1537, Muneharu was born in the village of Shimizu in the Kaya District of Bitchū Province. His childhood name was Saitarō.
Muneharu was a retainer of a gōzuku, or wealthy family, in Bitchū, first serving as a lord of Bitchū-Shimizu Castle and, later, as the lord of Bitchū-Takamatsu Castle. Although the details are uncertain, during the Bitchū Conflict between the Mimura and Mōri clans from 1574 to 1575, he sided with the Mōri clan even though he was the son-in-law of Ishikawa Hisatomo, a powerful hereditary retainer of the Mimura clan. Following victory by the Mōri, Muneharu became the lord of Bitchū-Takamatsu Castle.
The Bitchū Conflict was a major event between the Mimura and Mōri clans involving battles across Bitchū Province. In addition to Muneharu, other retainers of the Mimura sided with the Mōri based on their situational assessments. Mimura Chikanari, for example, was a member of the Mimura family, but sided with the Mōri.
There is a theory that, in 1565, Muneharu betrayed the Ishikawa clan who were hereditary retainers of the Mimura and took-over Takamatsu Castle, becoming a direct retainer of the Mōri. At this time, however, the Mōri clan exercised their governance of Bitchū indirectly, having delegated the province to the Mimura, so this theory is not compelling nor substantiated by primary sources concerning the history of Bitchū.
In either case, after becoming a retainer of the Mōri, Muneharu served under the command of Kobayakawa Takakage, contributing to the pacification of the Chūgoku Region by the Mōri. Diligent and loyal, Muneharu was deeply trusted by Takakage and the other leaders of the Mōri.
In the fourth month of 1582, after Hashiba Hideyoshi launched the Invasion of Chūgoku in furtherance of the plans of Oda Nobunaga to unify the country, Muneharu holed-up in Takamatsu Castle to resist in an event known as the Siege of Bitchū-Takamatsu Castle. For his surrender, Hideyoshi offered Muneharu control of Bitchū and Bingo provinces, but Muneharu did not accept and, instead, sent the vow from Nobunaga to his lord, Mōri Terumoto, and reiterated his loyalty to the Mōri.
As a result, the besieging forces proceeded with a plan devised by Kuroda Yoshitaka to flood the castle, and, just before the castle fell, Terumoto, along with Kikkawa Motoharu and Kobayakawa Takakage headed toward Takamatsu to aid the defenders, causing the opposing armies to enter into a stalemate. In the midst of the attack by flooding, on 6/2 of Tenshō 10 (1582), Oda Nobunaga died in a coup d’état launched by Akechi Mitsuhide in Kyōto in an event known as the Honnō Temple Incident. After learning of these developments, Hideyoshi concealed the news and offered to spare the lives of the defenders if Muneharu agreed to sacrifice himself. Unaware of the coup against Nobunaga, two days later, on 6/4, Muneharu, along with his older brother (Shimizu Munetomo), his younger brother (Nanba Munetada), and vice-general (Sechika Nobuyoshi), committed seppuku on a boat in the flood waters. He was forty-six years old.
His grave is at the Seikyō Temple in the city of Hikari in Yamaguchi Prefecture.