Anyone know this manga

I can't remember if it's yaoi or shounen ai or whatever. It's about this guy liking his senpai back in high school who was in the karate club(I think). He found him and when he did he found out his senpai liked another senpai in the karate club and wanted to be with him. To do that he became a woman and now they live happily. Well the guy moves in the same apartment complex as them and yeah I don't remember the rest.