The Imperial House of Japan is like a big family that has been around for a really, really long time. They are sort of like a King and Queen family, but they are called an Emperor and Empress.
The story of the Imperial House started a very long time ago in Japan, way before cars and computers even existed! Over the years, a lot of Emperors and Empresses have been a part of this family, and they have seen many things happen in Japan during this time.
Nowadays, the current Emperor and Empress of Japan have a very special role in the country, and people in Japan look up to them as important leaders who represent the whole country. They don't make laws or run the country, but they are still respected and seen as important figures.
The Imperial House is a big part of Japan's history, and they continue to be an important part of Japan's culture and traditions even in modern times.