noun
Refers specifically to the Tokyo Yūshun, a premier Japanese horse race for three-year-old thoroughbreds, commonly called the Japan Derby.
日本ダービーは毎年5月に東京競馬場で開催される。
The Japan Derby is held every year in May at Tokyo Racecourse.
ダービー alone can refer to the Epsom Derby or other derby races; 日本ダービー specifies the Japanese race.
Compound of 日本 (Japan) and ダービー (Derby), borrowed from English 'Derby', referring to the classic horse race.