He's one of the referees of the tournament --notice another one refereeing and the rest seated in the background. He doesn't take part in the tournament, he just challenges you if you show very good skill and if you get lucky --or rather unlucky. He says please more like because he wants to be sure the fight is fair, not that he's not a killing machine.
EDIT: I'm talking about Samurai Shodown
II,
needless to say.