Stationed In Japan
noun
Something or someone resident in 日本 (Japan) is stationed in Japan.
駐日 is generally used to describe both individuals and institutions stationed in Japan for official duties, such as the 駐日大使 (Ambassador to Japan) or 駐日大使館 (embassy stationed in Japan).
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
今夜は駐日アメリカ大使主催のパーティーに行かなくちゃいけないんです。
I have to go to a party tonight that is hosted by the U.S. Ambassador to Japan.