noun
western citadel; west wing of Edo Castle
Historical term referring to the western compound of Edo Castle, traditionally the residence of the heir apparent or a retired shogun.
See also: 江戸城
江戸城の西の丸は、将軍の世子や大御所が住む場所だった。
The west wing of Edo Castle was where the shogun's heir or the retired shogun lived.