Son, a bronze medallist at last month's World Championships, leads the men's seedings and is eager to recover from crashing out of last week's Korea Open in the semi-finals.

The world number one suffered a shock defeat against unseeded Indonesian opponent Anthony Sinisuka Ginting on home soil but opened his campaign by brushing aside home favourite Yu Igarashi 21-13, 21-13 at the Tokyo Metropolitan Gymnasium.

Seeded second, China's Shi Yuqi avoided a scare as he came from a game down to beat Brice Leverdez.

The Frenchman took the opening game 21-19 before Yuqi's quality shone through as he recovered to win the second and third 21-6, 21-16.

Denmark's world champion Viktor Axelsen also made a strong start to the tournament, making it through to round two with a 21-8, 21-13 win over Thailand's Tanongsak Saensomboonsuk.

Malaysia's reigning champion Lee Chong-Wei began his title defence with a three-game win.

Seeded fifth this year, Lee eventually proved too strong for Wong Wing Ki Vincent of Hong Kong and claimed a 21-15, 16-21, 21-17 success.

Chinese Taipei's Tai Tzu Ying is the top seed in the women's draw and she safely progressed to the second round.

Tai recently claimed the women's singles title on home soil at the Taipei 2017 Summer Universiade but did not need to take to the court today as her opponent, Japan's Haruko Suzuki, withdrew.

Japan's top-ranked player, Akane Yamaguchi, is also through but was taken to three sets by Jang Mi Lee of South Korea.

Yamaguchi came from behind to seal a 17-21, 21-15, 21-14 win.

PV Sindhu of India secured the women's Korea Open title in Seoul last week and also required three games to win.

The Olympic and world silver medallist overcame Minatsu Mitani of Japan 12-21, 21-15, 21-17.

Fifth seed Carolina Marin of Spain enjoyed a much more comfortable time on court.

The Rio 2016 Olympic champion clinched a 21-11, 21-11 win over China's Chen Xiaoxin.