One of the key stones mentioned in Tsukiyamateizōden (zenpen). According to that work, it is placed at the shore of a pond or a stream, with a hollow allowing water to flow underneath, forming a passage for fish. It is sometimes called yūgyoin.
Japanese Garden Dictionary: A Glossary for Japanese Gardens and Their History
(C) 2010 by Ono Kenkichi and Walter Edwards. All rights reserved.
