A revised Imperial House Law took effect on the 24th, allowing female members of the imperial family to remain in the household after they marry and permitting the adoption of male-line male descendants of former imperial branch families. The Imperial Household Agency will now work through the specifics.
The law stops short of allowing a female emperor. Japan's succession rules still admit only men in the male line, and the revisions leave the question of how to secure future heirs unresolved.
Under the current system, female members of the imperial family lose their royal status when they marry a commoner. The change lets them keep it.
The adoption provision applies to male descendants of the former branch families, or kyū-kazoku, who left the imperial family after the Second World War. It would restore a pool of male heirs outside the main line.
With the law in force, the Imperial Household Agency is to begin the detailed work of putting the changes into practice.