@vcnomnom Kei alsp lost 15% of "her" height. I don't think it's even the same person unless the fiction world they live in has advanced DNA body clone services or some kind of magic. It could also be Kei's mind swapped with another person that wanted to be a boy?
Author wanted to do serious topics, maybe it actually is a girl that made a deal with the real Kei that they would swap lives or she would take on Kei's past to help his friend. Because the part where she's living alone is pretty suspect. If the parents were around they could prove or disprove the girl's claims as to her identity.
As for MC, if the trap is a solid 9, just go for it.