Confirmed via Twitter, she was killed in a car accident.
Source: https://twitter.com/...330804126326784
Condolences to her family.
UPDATE: I didn't get a chance to update the post. Apparently she had an aortic rupture.
Source: https://twitter.com/...423557984256006
Other sources: https://kotaku.com/1820533763
http://www.asahi.com...KCKUTIL00Q.html
http://www.sankei.co...1170021-n1.html