Mikazuki Mao wa Seibetsu o Erabenai

After breaking up with her boyfriend who turned out to only want her for her chest, Mao wakes up the next morning in a male body. She finds out a witch cursed her family so sometimes they change sexes (her dad once lived as a woman too), but he tells Mao that they have plenty of time to decide what gender they want to live as. Mao decides to live as a boy like their kind dad, and moves to a new school where they live in the boy's dorm. However, Mao starts to crush on their roommate, Ryuusei