Being Gay in APAC Offices

I don't know much about Hong Kong (from what I understand they were probably the most liberal of Asian hubs but I know China's influence has become more noticeable in recent years) but if you go to Japan you are most likely going to have a hard time. While they don't have any outright laws that are anti-gay, culturally they still very much are and most domestic Japanese over the age of say 35-40 are anti-gay to the degree they would be considered alt-right by US standards. You'll have a hard enough time putting down real roots as a foreigner if you don't speak the language fluently and understand the customs well. If you add being openly homosexual into the mix it's going to be even harder to assimilate unless you manage to find a group of fellow gays in Tokyo to hang out with most of the time. You can forget about being treated well beyond basic courtesies outside of big cities if you are open about it and if you're in a small rural area, potentially not even that.

In general, in a professional setting for most Asian countries you will want to keep it to yourself. If someone shows interest/asks about your personal life you don't need to lie per say, just don't offer it up without someone explicitly asking if that makes sense. Your superiors are not going to celebrate it or give you any "diversity points" like you would get in NYC, and while they may not discriminate to your face there is a real risk of professional cost behind the scenes with any older seniors you work with if they're aware of it. Maybe not just because you're gay (I like to think a lot of places are past that level of pettiness), but if you were to let a ball drop or screw something up you will been looked at more negatively than if it were not the case. 

EMEA - You're talking about a region with many countries that explicitly ban homosexuality and that is even less culturally accepting of it than most of Asia. So yeah, probably not a great idea if you're not ok with hiding that part of your personal life unless you're exclusively working in the most westernized areas. And even then, you will likely face orders of magnitude more in-your-face discrimination than you would in even the most right-leaning parts of the US or Europe (except maybe Russia/Hungary).

I know these probably aren't the answers you wanted to hear, but the fact is unless you're in Europe or the US/Canada, more countries and cultures than not are particularly unfriendly to gays.