I think Presidents Fillmore and Pierce began trading with Japan, so one of their consuls?
(As for presidents I'd guess Grant, I believe he was in Japan)
Re: "...the first person to be allowed the privilege of shaking hands with the Emperor of Japan" - is there a taboo regarding this? I.e. never anyone was allowed to shake hands with him before? This is a serious question as I am always interested in traditions of other people and cultures!