inside the Imperial Palace
Refers to the interior or grounds of the Imperial Palace in Tokyo. Often used in news or formal contexts.
New Year's celebration events were held inside the Imperial Palace.
Department of the Imperial Household
Abbreviation of 宮内省 (くないしょう), the historical government body managing imperial affairs. Now replaced by the 宮内庁 (くないちょう, Imperial Household Agency).
See also: 宮内省
Before the war, the Imperial Household was administered by the Department of the Imperial Household.
court officer (Imperial Household Department)
Compound of 宮 (みや, 'palace') and 内 (うち, 'inside'). The reading くない is a Sino-Japanese on'yomi combination.