That's probably not the one you're looking for. It's the only manga about a fudanshi that comes to my mind though, so...
http://www.mangago.me/read-manga/fudanshi_baby/
If you find it I want to read it!
Try to find with the keyword fudanshi :D mebbe thatll help i dunno xD
Well this manga has a fudanshi uke and it's cute:
http://www.mangago.me/read-manga/mousouka_koi_o_suru/
http://www.mangahere.co/manga/ikenai_mousou_fudanshi/
This one is about a fudanshi and it is pretty funny!
So I'm not sure if this is the main story or a side. It's about how a guy reveals that he loves reading yaoi to a group of girls and they then become friends. He finds out and calls himself a 'fujoshi.' After that some romance happened I think with a male classmate. Can't remember anything except that the uke is a fujoshi! UHHHH!