One character (stone embankment) - Ichimonji

...Saiki, the central settlement in a small basin, was the fief of the Tsuchikura clan, the chief retainer of the Okayama domain in the early modern period, and its jin'ya was located here. It also flourished as a river port on the Yoshii River. The gorge near the river was a difficult spot for boats sailing along the Takase River, and a stone embankment called Ichimonji was built to ensure safe navigation. Agriculture, mainly rice, is the main industry, and the area is known for its specialty products such as matsutake mushrooms, kampyo, and konjac.

*Some of the terminology explanations that mention "Ichimonji (Stone Embankment)" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…小盆地に開ける中心集落の佐伯は近世岡山藩の家老土倉氏の封地で，その陣屋が置かれ，吉井川水運の河港としても栄えた。河瀬付近の峡谷は高瀬舟航行の難所で，一文字と称する石堤が舟航安全のため築かれていた。米作主体の農業が主産業で，マツタケ，カンピョウ，コンニャクの特産がある。…

※「一文字（石堤）」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報