South Korea's unstoppable An became the first woman badminton player to win two singles titles in Games history after dominating home hope Akane Yamaguchi 21-17, 21-9.
The reigning Olympic and world champion has not lost a match since March and added the Aichi-Nagoya crown to her Games title from China three years ago.
"It really does feel like a dream, I am so happy. Everything I put into it keeps coming back to me, it is overwhelming," said th…