Japan's reigning world champion Kento Momota won his first Japan Open title on Sunday, beating Thailand's Khosit Phetpradab in straight games.

Japanese duo Yuki Fukushima and Sayaka Hirota also won their maiden championship in the women's doubles. Nozomi Okuhara settled for silver after losing to 2016 Rio de Janeiro Olympic gold medalist Carolina Marin of Spain in the women's singles.

World No. 4 Momota defeated No. 26 Phetpradab 21-14, 21-11 in the 48-minute match at Musashino Forest Sport Plaza, the venue for the 2020 Tokyo Olympic badminton competition.

Momota, competing at this meet for the first time in three years, dragged Phetpradab across the court and bagged six straight points to seal the win.

"I didn't imagine myself winning this tournament when I played three years ago," he said. "I won my dream competition with the support of many people. I'm glad I showed my home fans that I have grown."

"Winning a competition at (this gymnasium) seems like a sign of good fate. But I want to focus on my upcoming matches rather than concentrating on the Olympics," he said.

The Japanese ace defeated world No. 1 Viktor Axelsen of Denmark in Saturday's semifinal, following his 2-0 win over two-time Olympic gold medalist Lin Dan of China on Friday.

The 24-year-old, who was only restored to the national team in January after a suspension for illegal gambling, became the first Japanese man to win a badminton singles world championship in August.

In the women's doubles, Fukushima and Hirota beat China's Chen Qingchen and Jia Yifan 21-15, 21-12.

In a hard-fought women's singles final, Okuhara fought back from a first-game deficit against defending champion Marin. But she failed to pick up the momentum in the third game, losing 21-19, 17-21, 21-11 in 1 hour, 15 minutes.

The six-day Japan Open is one of five Super 750 tournaments on the World Tour. The tour consists of 26 meets held across the world, and the top eight players or pairs in each discipline play in the season finale in December.