This famous quote was never atributed to Emperor Hirohito.
It was however, MISTAKENLY attributed to Imperial Japanese Admiral Isoroku Yamamoto, base on the movies "Pearl Harbor" and "Tora! Tora! Tora!". However, there is no historic information or records that show the Admiral had ever said anything like this at the outset of World War II...though he may have well personally thought of it.
And as everyone knows, there is a world of difference between the Emperor, Hirohito, and the Supreme Admiral of the Japanese Imperial Navy, Admiral Yamamoto. It would be akin to confusing President Truman with Douglas MacArthur over a quote.
“Never trust what you read on the internet. People make up quotes all the time!” — Thomas Jefferson, 1867.
Another quote attributed to Hirohito is something to do with “a gun behind every blade of grass”...who actually said that?