Transsexual? Oh sorry transvestitemegagiganticvibrator. Seriously how many other world people does this world get each year that everyone and their grandma knows about it.
It's too early to tell right now, but I'd say the MC would be somewhere between the incompetent Dan and stiff as a board Ryu. Maybe Ken or Ryo (Sakazaki from KoF).
I think i prefer this kind isekai than isekai with high school boy that got cheat skill then want stay easy going and lay low and in 3 chapter already get his harem. And too much echi scene to.
ah, yes... as a karate practitioner myself I know too well about being a kumite junkie. People at my dojo will literally get a boner when fighting national champions/strong karatekas.