The Mainichi Hai is a Grade 3 horse race for three-year-old Thoroughbreds run in March over a distance of 1800 metres at Hanshin Racecourse.

Hanshin Racecourse is located in Takarazuka, Hyogo, Japan. It has a capacity of 139,000 and it is used for horse racing. The land was originally owned by Kawanishi Aircraft Company, which manufactured combat planes during World War II. After the World War II, GHQ ordered the company to stop manufacturing combat planes, which ended in closing the factory. In 1949, Keihanshin Keiba K.K. built the Hanshin Racecourse. The racecourse was transferred to Japan Racing Association in 1955. A major reconstruction was completed in 1991, and another in 2006.