Japan women's international forward Kumi Yokoyama has come out as a transgender man and says they want to help raise awareness in their home country.

The 27-year-old, who plays for National Women's Soccer League (NWSL) side Washington Spirit, said living in the United States and Germany had shown that it was possible to be more comfortable with their identity.

They were speaking in a video interview on former team mate Yuki Nagasato's YouTube channel.

Yokoyama had surgery to remove breast tissue seven years ago without hormonal treatments, as that would have meant there was a risk of failing doping tests, and plans to undergo more gender-affirming procedures after retiring as a player.

"I've dated several women over the years but I had to stay closeted in Japan," Yokoyama said in the interview, which was translated by the Japan Times.

"In Japan I'd always be asked if I had a boyfriend, but here (in the U.S.) I'm asked if I have a boyfriend or girlfriend. When my girlfriend said there was no reason for me to stay closeted, it really hit me.

"Coming out wasn't something I was enthusiastic about, but if I think about my life going forward, it would be harder to live closeted so I found the courage to come out."

A tweet from the Spirit said Yokoyama would use the gender-neutral pronouns "they" and "them" going forward.

Yokoyama, who played for Japan at the 2019 Women's World Cup in France, said that Canada international and OL Reign midfielder Quinn's decision to come out as transgender last year was an inspiration to them.

"(Quinn) wore a (sweatshirt) that said 'Protect Trans Kids' before a game, and I realized that's what taking action looks like," Yokoyama said.

"Lately the word 'LGBTQ' has become more commonly known in Japan and been covered by the media, but people in my position aren't able to raise our voices and talk about it.

"If all of us speak up together then we can help raise awareness."