Does anyone know

Does anyone know this manga where the guy/girl can choose what gender they want to be cuz of something in their blood and then they get teased a little but the the guy does some posters to explain what he is and he likes another guy but the other guy can't own up that he likes him so he just leaves a bag of food on the door where he is and I think he sends him letters so if you've read it or seen it some where plz tell me