I am sure this was right after Japan apologized for Pearl Harbor, the Bataan Death March, Cabanatuan, etc., etc., etc., no?
Are we going to apologize for all those maybe a million Japanese lives that were saved when Hiroshima and Nagagsaki were hit?
No one knows how many Americans would have died in the invasion. It says right here that many more than 200,000 Japanese would have died in the same invasion.
...the rape of Nanking
...the rape of Nanking
For what it is worth, Japan has made about 50 official apologies since the 1950s regarding various aspects of the Pacific War, and its actions in Korea and China. There's a list at List of war apology statements issued by Japan.
In fact, just last year, there was a specific apology for the Bataan Death March, delivered directly to 73 of its survivors: Japan Apologizes for Bataan Death March.
But there's no reason for us to apologize. Japan had its own nuclear weapons program, and there is significant research that shows that they were much closer to a weapon than most historians had thought. (There are even some people who believe that Japan had actually succeeded with some version of a nuclear weapon test in what is now North Korea.) There's no question in my mind that if the Japanese could have used a nuclear weapon on us, they would have not hesitated to do so.
It was a hard-fought war by both sides. From talking with many Japanese, I have myself met very few that felt aggrieved by the nuclear weapons used at Hiroshima and Nagasaki. (I would say, though, that an irrational horror of nuclear weapons is quite common among Japanese.) I believe it's safe to say that every one of those folks who I met that were vocally aggrieved were quite leftist, and well out of the Japanese mainstream.