Naomi Osaka is feeling "a little bit refreshed and happy again" after returning to tennis with a convincing 6-1 6-4 triumph over Zheng Saisai in her Tokyo 2020 opener.

The four-time grand slam winner has not featured since the first round of the French Open two months ago where she abandoned her campaign following a warning she risked expulsion over her refusal to take part in news conferences during the tournament.

Osaka, who is the reigning US and Australian Open champion, then decided to skip Wimbledon after opening up on her battles with anxiety and depression.

The 23-year-old was granted the honour of lighting the flame for Tokyo 2020 on Friday and two days later made a successful return at the Ariake Tennis Park, where she represents one of Japan's greatest medal hopes for the Games.

"I feel like, more than anything, I'm just focused on playing tennis. This, playing the Olympics, has been a dream of mine since I was a kid, so I feel like the break I took was very needed," she said.

"But I feel definitely a little bit refreshed and happy again.

"I felt really nervous being in Japan and playing here for the first time in maybe two years, and for it to be my first Olympics. 

"It was definitely really nerve-wracking. But I am glad I was able to win, she is a very tough opponent.

"It's been a while since I played but I feel, more than anything, just happy to be out here. We are playing in a pandemic, and it is really tough for everyone."

Asked how she felt to be talking to the press again, she said: "For me, honestly I don't feel that weird about it.

"It might feel weird to you guys, but I don't know. I'm happy that I guess you guys are asking me questions but more than anything I was just focused on playing tennis and I guess I feel a little bit out of my body right now."

Osaka then revealed that her starring role in Friday's opening ceremony came about in March.

"I was super honoured," she said. That’s a position you dream about and not anyone can do it so when they asked me if I wanted to I was very surprised but very honoured and I'm just happy to be here and happy to play, especially in Tokyo."

The playing conditions have been a quite literal hot topic over the first two days, with the sweltering heats causing issues for players.

Daniil Medvedev and Novak Djokovic were among those to speak out about the decision not to play matches later in the day Tokyo, where temperatures have regularly been above 30 degrees.

Osaka, though, has no such issues, adding: "It feels fine for me. I have played a couple of tournaments here, of course they resurfaced it since I was last here, but I love being here, and I actually really like the weather."