The bubbly 21-year-old's achievement in New York made her the first player from her country to win a major, and with it came fanatical support.
She's not complaining, but took precautions when back there recently.
"I mean, I didn't really walk outside. I just went in the car and stuff," she said after winning through to the quarter-finals of the Australian Open on Monday.
"When I did, I went at night and had a wig on. For me, it was very fun."
She said the wig was her sister's idea.
"She was, like, 'You know what you should do? You should bring this wig and if you want to walk around, just throw it on and put on some sunglasses'.
"I personally think she was making it a bigger deal than it had to be. Honestly, I feel like people don't look at other people when they're walking around," she added.
"I get that I'm tan and I would stand out a little bit in Japan. But I think the only way people would really care is if I'm wearing some sort of athletic gear, if I was walking around with my tennis racquet."
Osaka's mother Tamaki is Japanese, but her father Leonard is from Haiti, one of the poorest countries in the world.
While Osaka is a frequent visitor to Japan, she hasn't spent much time in Haiti.
But each time she has been back has reinforced how lucky she is.
"For me, it's a very humbling experience to go back, because you see so many people that don't have much, and then you go back to your house and everything that you take for granted you start appreciating it more," she said.
"Because when you go there and you see people, like, literally, they have to walk miles for water and it's just like, 'Why are you complaining about your life'? Yeah, for me, I felt very grateful to go there."