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traditional square chair with armrests and a torii-shaped back (used by the emperor, etc. during ceremonies)
倚子は格式高い椅子だ。
An ishi is a chair of high formality.
この倚子は天皇が使ったと言われている。
This traditional chair is said to have been used by the emperor.
博物館で見た古い倚子の彫刻がとても美しかった。
The carvings on the old traditional chair at the museum were very beautiful.