Androgyny is definitely an aesthetic thing in jap culture. Where the west had corsets and poofy dresses, japan had kimonos, which are basically oversized robes that hide one's figure. And both sexes wear them.
Apparently it mostly stems from this:
https://en.wikipedia.org/wiki/Oyama_(Japanese_theatre) basically they had (often erotic) theatre, and the actresses were prostitutes as well and there were various problems surrounding that. So female actors were banned, and all female roles were played by young/effeminate men. Who were also prostitutes and much sought after by the patrons. Except now the women want to fuck them too.