The law enacted at the end of last week means that the Emperor’s abdication must take place within three years. The last emperor to abdicate was Kokaku in 1817. As it stands only men from the paternal bloodline can rise to the position of Emperor and the country’s Prime Minister Shinzo Abe's government supports male-only succession. Emperor Akihito's 57-year-old son, Crown Prince Naruhito, is next in line.
Debate about female succession
The debate as to whether woman can ascend to the position of Emperor continues and is likely to be challenging to many as Crown Price Naruhito's only child is a girl, and his younger brother, Prince Akishino, has two adult daughters and a 10-year-old son, Hisahito meaning that only one of the Emperor's four grandchildren is currently an eligible heir. After Naruhito's daughter was born the possibility of allowing female ascension was a topic of debate but onw that floundered after Hisahito's birth but many have concerns about a shortage of heirs.