At the 2017 World Table Tennis Championships, Niwa partnered with Maharu Yoshimura to win the bronze medal. The Niwa/Yoshimura pair reached the semi-finals where they lost to Chinese pairing and eventual champions Fan Zhendong and Xu Xin in the men's singles event, he reached the quarter finals, defeating Dimitrij Ovtcharov in the fourth round, and losing to Fan Zhendong in the quarterfinals.