I presume your talking about the Tatsuya Souma one. It's official, or at least semi-official. It was serialized in a Bandai-owned comic magazine.
Really? I thought it was more of a fan-made thing.
There was also another semi-official manga serialized in Comic Bombom magazine. I don't know much about it, though.
Are you talking about the one by Hamada Yoshimi?