A transgender manga? My favorite it has slight bl, enemy to lovers m, emotional, and heartwarming. So in this society boys will suddenly become females to even out the population of females to males. 2 guys best friends have a rivalry relationship. One guy is suddenly a female. They try to be friends but it becomes more than the female turns back into a male but becuase they wish to stay female to be together they sleep for 5 years. Their relationship develops and learn more about the transformation they get married and have a cute daughter.
Kanojo Ni Naru Hi