Sasanomaru Castle Ruin
[Location] Yokosu, Yamsaki Town, Shiso City
Uno, the acting governor of the Akamatsu Clan in Nishiharima, had his residence built in Hirose, Shiso-gun (central part of Yamasaki Town). Sasanomaru Castle was built on top of the mountain behind it. According to "Akamatsu-ke Banbisaku-jo-ki (Report on Castles Related to the Akamatsu Clan in the Harima, Bizen and Mimasaka Provinces during the Middle Ages)," the castle was first built in the Nanboku-cho Period (1336-1392) by the eldest son of Akamatsu Sadanori, Akinori.
The main rectangular kuruwa (area surrounded by a moat, an earthen wall, or a stone wall), which is 40 meters to the east and west and 50 meters to the north and south, is located at the east end of the massif (Mt. Sasa with an altitude of 324 meters) that stretches from the northwest. There are earthen walls and dry moats on the west and south sides of it. Currently, the opening in the central part of the earthen wall on the south side serves as the “entrance/exit.”
Along the ridge on the west side of the main kuruwa, between pathways on the north and south sides, are square shaped kuruwas. The west end of the ridge is blocked with three rows of dry moats. On the north side of the main kuruwa are two lines of square shaped kuruwas placed in tiers along the ridge. There are pathways on the east and west sides of them.
The most distinctive feature of this castle ruin is that multiple dry moats were dug vertically along mountainsides, creating ridges, on the gentle slope on the north side, from the north end entrance to three rows of dry moats at the west end. With additional dry moats dug around kuruwas, earthen walls, and pathways that guard the north and west sides of the castle, it was a castle ground with a rare structure. While vertical dry moats were not dug at the main Chozui Castle, the use of stone walls seen at the Chozui Castle was not confirmed at the Sasanomaru Castle.
It is said that during the Sengoku Period (1467-1568), the eldest legitimate son of Uno Masayori, Mitsukage, became the castle lord. However, due to a conflict between the father and son, Masayori disinherited and murdered Mitsukage in 1574. Then a retainer, Utsumi Sahyoe, was stationed at the castle to guard it, but the castle fell to the forces of Hashiba Hideyoshi together with Chozui Castle in 1580.
The official historical document of the Kuroda family, “Kuroda Kafu (The Genealogy of the Kuroda Family),” states that Kuroda Kanbe lived in the “Castle of Yamasaki” after the death of Uno, which led to a theory that the castle he lived in was Sasanomaru Castle. According to authentic historical materials, Kanbe ruled Shiso from July, 1584, to July, 1587, until his relocation to Buzen.
It is stated in “Shiso-gun Shurei Kotai-ki (Record of Changes of Magistrates in Shiso County),” which was written in 1699 of the early Edo Period, that “officials and magistrates lived here.” It can be assumed that magistrates lived in the castle in place of busy Kanbe during the normal times.
Reference Materials:Includes “Hyogo-ken no Chusei Jokan/Syoen Iseki (The Ruins of Castles and Manors from Medieval Times in Hyogo Prefecture)” edited by the board of education of Hyogo Prefecture
This signage was installed by utilizing “The Local Dream Promotion Project.”
--Counselor of Nishiharima Prefectural Government Rejuvenation Committee--