Red means go...

At least if there's a green arrow pointing in the direction you're going underneath it. Usually, I see a red light with an arrow pointing right or something which makes some sense. I just assume it is a protected arrow so that people can safely cross traffic. Today, though, I saw a red light with all possible green arrows lit (left, right, straight). Why bother with the red light? I don't quite get the Japanese traffic signals just yet. I guess I should just be thankful that I know not to stop for the red circle and can keep my fellow drivers at least that happy.