Ahhh, this is it! This is the page! This single page was inserted into the inside back cover of an issue of Electronic Gaming Monthly as an ad for some manga import service, years and years and years ago, probably literally 30 years, and it changed my life!, by introducing me to
Manga. It introduced me to manga. Sorry did you think I was gonna say something else
Rumiko Takahashi knows what trans people are!!!
(Explanation: For screwball comedy reasons, Ranma needs to convince Shampoo he is a girl transformed into a guy rather than a guy transformed into a girl. His dad and dad in law, who fully understand Ranma's curse situation, take this seriously, which can only be explained if they think Ranma is coming out as trans. … Unless Takahashi is just making a joke about the dads being really dumb. But Panda Dad isn't THAT dumb.)