Hirohito was the Emperor of Japan during World War II. He sought revenge for his defeat by brainwashing the children of South Park using the Chinpokomon toys and games, and having them bomb Pearl Harbor. His plans were eventually foiled by the parents of South Park. He was succeeded by his son, Akihito.
Hirohito is also known for his distinctive technique of distraction, whenever someone troubles him he makes a quick comment on the person's penis size, describing it as being large and gigantic, and his own penis being small and tiny. This method turns out to be very effective, Bill Clinton as an example has been fooled by him.