The first outfit isn't a dress as you can see she's wearing pants on page 6 as for the second one pages 8 and 10 sort of seem to indicate that the outfit is one entire cloth but the bottom portion seems to lean towards being pants too. Although for a character established as a bigtime delinquent...
This reminds me of Kimi ni Aisarete where the bully got gang raped and I was more invested in her story until the author decided to pretty much erase her from the manga
I'm glad the author had the MC get freaked out from being seen in the bath because the fact they were a girl might be discovered. Usually in TSF manga and author seems to forget that the MC was supposed to be male and has them get embarrassed because they are being seen naked by a guy.
Honestly is you get past the fact of the masochistic MC this manga is pretty fucked up I mean MC got transported almost immediatly made a slave, stripped of clothing, and now has her belongings either being destoryed or sold