The FL younger twin brother fell inlove with a girl that went abroad to Australia so he decided to follow her but to do that he had to switch lives with his sister. He made his sister the FL pretend to be him so he wouldn’t be absent at his school. The moment the FL got their there was the ML that treated her super nicely and the FL made him fall so hard for her that the ML thought that he WAS GAY.
It is really cute but mio could be of any gender and it would make little to no difference to the story but hey that's how gender bender works. Anyway it really has been a while since I enjoyed a shoujo manga as much.