The Chugoku region (中国地方; Chūgoku-chihō) is located within the western region of Honshu, the largest island of Japan.
It consists of following prefectures: Hiroshima, Yamaguchi, Shimane, Tottori. Okayama is sometimes included or excluded for some reason.
In Japanese, the word "Chugoku" is is also used to mean "China", which sometimes leads to confusion.