Chiaki Mukai (向井 千秋 Mukai Chiaki?, born May 6, 1952, Tatebayashi, Gunma, Japan) is a Japanese doctor, and JAXA astronaut. She was the first Japanese woman in space, and was the first Japanese citizen to have two spaceflights. Both were Space Shuttle missions; her first was STS-65 aboard Space Shuttle Columbia in July 1994, which was a Spacelab mission. Her second spaceflight was STS-95 aboard Space Shuttle Discovery in 1998. In total she has spent 23 days in space.
Mukai was selected to be an astronaut by Japanese national space agency NASDA (now called JAXA) in 1985. Prior to this, she was an assistant professor in the Department of Cardiovascular Surgery in Keio University, the oldest university in Japan.