Looking for this old manga about ABO intersex

Apparently it’s the world where you can be a gender but it’s permanent once you choose. The MC is gender less and it’s in ABO world I think(?) alpha omega beta type of stuff or not I forgot. But I remember there’s MC, short hair/looks kinda boy ish to me. And he has two childhood friends—girl and boy.

The girl wants MC to be a boy and the boy wants MC to be a girl, they want him to choose. Both like MC.