
I think it means a crossdresser as seme.

I just guessed, but it is one kinda like, isn't it!? ;-)

Really? ‘cause once in a while I stumble over this topic (or “josou” in the title) it has a crossdresser in it. So I guessed that thing is combined with crossdressers. Plus “Hentai Wiki” (it seriously exists) says: Description: A crossdresser or tomgirl taking the lead / being dominant over a sexual partner. Note: Requires either tomgirl or m: crossdressing.
Well, anyway … crossdressers are feminine, so … ;-)

So, "Hentai Wiki" needs an update! :-D
Thank you for the explanation.

Oh sorry super late reply. So far all I know about josou seme is, it's a term for crossdressing semes, it's a rarely used tagged since it is a farely new slang from what I've read (for foreigners it is since some are more familiar with the term crossdressing and lets face it that english term tags are often used rather than the japanese term tags). I'm not sure how often Josou is used in japan since there is also otokonoko but I saw a tv show "josou paradise" and well men crossdressing show (so i just assume yeah josou = crossdressing male). It also doesn't limit to shotas and being femenine, check out the new bl anthology "onee josouzeme bl" there are some big/manly crossdressers there.
Welp I just really like to use Josou seme than crossdressing seme since it's short and easier to type
Twincest and a josou seme, I am blessed.