imo, the story talks about people's different tastes or fetish. everyone has their own hobby/tastes/preference that sometimes doesnt suit to what society think is normal. in this story, the mc is a guy who loves high heels. he's not gay or a crossdresser, he just likes them. and whats wrong with that? the story also talks about lgbt relationship (the mc's sister) and fetishes and how society discriminate people with abnormal taste/hobby/preference.
Why Did Men Stop Wearing High Heels?