I was worried about it when I came to Japan, but when I tried to use the lady's because I was only three months on T, an old woman stopped me and said I was in the wrong bathroom. When I apologized she told me to be careful, lest someone think I'm a pervert and call the cops. So, I use the men's room now, when I have to. I hate public bathrooms in general so I try to avoid them. But if I gotta go, I just waltz in. I just a few stares, but I think its because I'm more of a "pretty boy" coupled with being a foreigner. I even used a men's room at Seatac airport and no one batted an eyelash. One guy gave me a funny look but I just shrugged and he didn't say anything.