It's not a bad theory.
R she could be friends with Gyul-Wool, that story totally relates to their situation and who the hell asks a traumatized bullied victim to tell u more of their story while looking so happy and she's been kidnapped for over a week how the hell could she smells good, even if he let her showered but y would he do that when she doesn't even have a bed in the room, just a lot of boxes. And for someone's who was kidnapped she sure is trusting to other guys even if he's a kidnapee
I thought she was gyuh-wool at first since when she was first introduced they were in a room together and she's so flat chested (I also thought he was the store clerk just in disguise though) so her being a guy wouldn't surprise me that much
i think the girl is actually a boy. i mean, she was talking about the Fox Story. that probably means "she's" trying to be someone else in order to make friends...tbh idk..