A key stone near the foot of a stone lantern, about the same size as a stepping stone, to stand on when lighting the lamp. It is more ornamental than practical. It is also called tenkaseki and basin front stone (mae ishi), (def. 2).
Japanese Garden Dictionary: A Glossary for Japanese Gardens and Their History
(C) 2010 by Ono Kenkichi and Walter Edwards. All rights reserved.