Kamahajō Castle

Overview and Location

**Kamahajō Castle** (鎌刃城) is a mountain fortress located in Banba, Maibara City, Shiga Prefecture, rising 384 meters above sea level with a relative height of 250 meters. It served as a critical "boundary castle" (sakaime no shiro) dividing northern and southern Ōmi Province during the conflicts of medieval Japan. The castle complex spans approximately 400 meters east-west and 500 meters north-south, with 17 enclosures (kuruwa) arrayed along ridges radiating from the main citadel (honmaru). The castle's name derives from the razor-blade-shaped ridge near the Seiryū Falls on the southern spur. Designated a National Historic Site in March 2005 and selected as Continued 100 Famous Castle No. 156 in 2017.

Construction and Medieval Lords

The precise date of Kamahajō's construction is unknown, but it is thought to have been built around the time of the Ōnin War (1467) to control the strategic boundary between northern and southern Ōmi. A 1472 document records an attack on the "Hori Jirō-zaemon," confirming the castle's existence by that date.

The most clearly documented early lord was the Hori clan (said to be descended from Fujiwara no Hidesato), who controlled the Banba post station and governed northern Ōmi from Kamahajō. In 1538, the castle fell to Rokkaku Sadayori's forces and passed temporarily under Rokkaku control, though the Hori clan continued to maintain a presence in Ōmi.

Hori Hidemura, Higuchi Naofusa, and Oda Nobunaga

Two figures define the castle's final years: its last lord, Hori Hidemura, and his chief retainer (karō), Higuchi Naofusa, described by contemporaries as "Ōmi's greatest strategist." Following the early death of Hidemura's father, Higuchi effectively managed clan affairs. He is also noted for sheltering Takenaka Hanbe Shigetsugu (the famous Sengoku tactician) when Takenaka briefly sought refuge in northern Ōmi after losing Inabayama Castle.

In 1570, as Oda Nobunaga's army marched north against Asakura Yoshikage in Echizen, the sudden defection of Asai Nagamasa threatened to cut off Nobunaga's retreat. At this critical juncture, Kinoshita Tōkichirō (the future Toyotomi Hideyoshi) persuaded the fifteen-year-old Hori Hidemura to switch allegiance from the Asai to the Oda. This defection allowed Nobunaga's forces to pass through northern Ōmi — a pivotal decision that set the stage for the subsequent Battle of Anegawa.

After serving the Oda cause, the castle was abandoned in 1574 when Higuchi Naofusa was arrested and executed by Hideyoshi on suspicion of colluding with an Ikkō Ikki uprising. Hori Hidemura was dispossessed but later pardoned, eventually serving under Toyotomi Hidenaga until his death in 1599 at age forty-three.

Structural Features and Archaeological Remains

Systematic excavation conducted by the former Maibara Town Board of Education (1998–2003) revealed Kamahajō's remarkable early stone-wall construction. The main enclosure features stone walls measuring approximately 4 meters high and 30 meters long — among the most significant pre-Azuchi stone wall remains in Japan, demonstrating pioneering masonry techniques for the era.

Particularly extraordinary is the castle's water supply system (mizu no te iseki). A channel carved directly into bedrock conveyed water approximately 700 meters from the Seiryū Falls into the castle via wooden conduits — a water infrastructure feature described as "nationally rare" (zenkokuteki ni mo mezurashii iseki) by researchers.

The western ridge features eight successive ridge-cutting moats (horikiri) and five vertical moat clusters (tatebori-gun), demonstrating thoroughgoing defensive planning. The foundation stones of a large pillar-supported building (ōyagura, or great tower) were also uncovered; its subterranean chambers have been interpreted as a precursor to the architectural innovations of Azuchi Castle.

Connections to Swords and Arms

Ōmi Province has long been a center of metalworking tradition; the heritage of Ōmi smithing (Ōmi-uchihamono) extends continuously from the medieval period. Banba post station, at the foot of Kamahajō, was a node of the Nakasendō highway and a key point for the movement of goods and people, including swords and military equipment.

During the period when the Hori clan served the Asai, the Asai lords patronized swordsmiths from Bizen and Ōmi, distributing blades to retainers as gifts of honor. The Tenshō-era arrival of Oda forces at Kamahajō would have introduced the finest contemporary swords and armor. Following the execution of Higuchi Naofusa and the castle's abandonment, its weapons and sword collection were reportedly seized.

Current State and Highlights

The Kamahajō ruins are maintained as a publicly accessible historic site by Maibara City Board of Education. Stone walls, ridge-cutting moats, vertical moats, and the water supply system survive in excellent condition, earning the castle a devoted following among mountain castle enthusiasts as "Ōmi's finest mountain castle." The Banba Historical Museum at the foot of the mountain (open Saturdays and Sundays, 10:00–16:00) exhibits excavated artifacts and sells official castle stamps (gojōin).

Access: take the Kokoku Bus from JR Maibara Station to the Banba bus stop, then hike approximately 50 minutes along a mountain trail. Visitors are advised to wear long sleeves and sturdy footwear and to be alert to wildlife hazards including bears, leeches, and wasps.