Gai is like gay but in a non-binary way. It is for non-binary people who's attraction is not to the same gender (due to the nature of non-binary genders), but is still not straight. Depending on the nature of one's gender and their attraction it can refer to several different things. It can refer to non-binary people who are attracted to women in a non-straight way (nblw), or non-binary people who are attracted to men in a non-straight way (nblm). It can also refer to non-binary people who are attracted to non-binary people (nblnb).
Flag
The gai flag was designed by Tumblr user Orbisian-princess some time around December 24, 2017[1]. Orange is for solarians, yellow is for non-binary people in general, green is for stellarians, blue is for multi-attracted non-binary people who feel gai towards more than one gender, purple is for lunarians.