The USS Arizona (BB-39) burning after the Japanese attack on Pearl Harbor, 7 December 1941 (from Wikipedia Commons, this image is in the public domain.)
Actually, most Japanese feel a little pang of conscience about the Pearl Harbor attack, in spite of them knowing that it was a perfidious attack. Of course, a perfidious attack is understood as an evil act among Japanese. Why do Japanese think that the Pearl Harbor attack was "a normal act?"
First, quite a few Japanese believe in the opinion that "the U.S. knew of the attack beforehand." The opinion is as follows: The U.S. caught and decoded the Japanese army's coded command of the attack, therefore the U.S. army prepared for the attack: let all main aircraft carriers go, only old battleships were left in the harbor. The opinion also says that a rare vivid color film which captured the attack exists. It is the evidence of the opinion, they said. In addition to, some go to the length of saying that it was a trap by the U.S. Of course, all the information above is a false rumor. But in Japan, many people know and believe the rumor.
Second, some Japanese say that the Japanese government prepared the declaration of war, but it couldn't be sent to the U.S. government before the attack. The night before the attack, all members of the Japanese Embassy in the U.S. attended a farewell party for a member and the ambassador attended a funeral, therefore nobody could receive the declaration. The ministry of foreign affairs of Japan admitted this mistake at last in 1994.
This mistake was a big misfortune for Japan: the attack became a perfidious attack from a mere sudden attack. However, at any rate, it was Japan's mistake - not the U.S.'s. In addition to, the Japanese government thought that the declaration of war would be sent at least 30 minutes before the attack. If Japan sent the declaration as they thought, the attack would be a perfidious one.
Third, in my opinion, this is the strongest reason for the Japanese thinking about the attack, nobody says that the Pearl Harbor attack was out of spite. Most Japanese think the following: Was the attack a surprise attack? Yes. Do you think the U.S. got angry? Yes, of course. That's all. People never ask the next question: Was the attack out of spite?
It is absurd thinking, I admit. However, in my opinion, many Japanese think so. Actually, I did. Through writing this article, I have learned that the rumor that the U.S knew of the attack beforehand was false, learned over 2,400 U.S. people were killed at the attack (many Japanese think the attack broke many battleships but didn't take people's lives.) I have also learned the following fact: think about what we did.
Why did Japan attack Pearl Harbor?