Japan adopts new imperial succession law, allowing male adoptions but excludes Princess Aiko

Japan’s parliament approved a historic amendment to the Imperial House Law on 17 July, permitting the imperial family to adopt male heirs from former collateral branches. The rule applies to male relatives aged 15 or older, reviving the possibility of incorporating descendants of erstwhile noble families that lost titles after World War II. The reform also allows female members of the imperial family to retain their status after marrying commoners, a change aimed at preventing the household from shrinking.

Despite the broader opening, the amendment leaves the ban on female succession untouched. Princess Aiko, the only child of Emperor Naruhito and Empress Masako, remains ineligible to inherit the throne. Former prince Asahiro Kuni publicly criticised the adoption provision as unrealistic and questioned its public acceptance. The change has sparked political debate, with opposition leaders accusing the governing coalition of pushing the revision without sufficient consensus, while the Emperor has expressed hope for public understanding.

The law was enacted by the upper house and is set to be promulgated on 24 July, with implementation slated for three months later, signalling the first substantive alteration to Japan’s succession rules in almost eight decades.