Sakai came off her motorcycle at about 4:20 p.m. on Jan. 15, and hit a fence. She died shortly afterward in a medical office at the venue. Officials said her cause of death was a fractured skull, and police are investigating the cause of the accident.
After graduating from university, Sakai started office work, but she later traded in her career to become an Auto Race competitor. In July last year she was one of two female racers to join the Japanese sport, marking the first time in 44 years for women to make a debut. She won her first race the following month.
JKA, a Tokyo-based foundation promoting the sport, said that another racer died during a race in September 2009 at the Iizuka Auto track in Fukuoka.