Emperor Naruhito, the new Emperor of Japan, ascended the throne on May 1, 2019, after his father, Emperor Akihito stepped down. His becoming the monarch also starts a new era, the Reiwa era, which means ‘peace and harmony’.
Does the Emperor rule Japan? No it is largely a ceremonial role. The government, headed by the Prime Minister of Japan, runs the country according to its Constitution.
Here is an infographic about this fascinating country: