It's just one of the technicians, although exactly who, I'm not sure.

All he is saying is 「それでは皆さん、よろしくお願いします。」 "Sore de wa minna san, yoroshiku o-negai shimasu.". It's basically just something you say when you are introducing someone or being introduced. It's kind of like saying "Thank you" for something someone is about to do for you(in this case: listen to the song). It literally means something like "I wish for the best".

He's just on the recording to give it more of a studio feel, and to set this song apart from the rest of the album (because it is a bonus/title track).