Japan opens door to male-line succession through adoption, bypassing Princess Aiko

Japan's parliament has overhauled imperial succession rules to prevent the royal line from dying out.

The upper house of the National Diet passed an amendment to the Imperial House Law on Friday, allowing men from former royal families to be adopted into the imperial family. The change means a male relative as distant as 36 degrees of kinship from Emperor Naruhito — sharing no blood with him — could eventually ascend to the throne.

The core of the amendment is that while an adopted man from a former royal family cannot himself become emperor, any son he fathers would receive succession rights as a male-line heir. It marks the first revision to the main provisions of the Imperial House Law — as opposed to supplementary clauses — in 77 years, since 1949. The amendment also allows female members of the imperial family to retain their royal status and remain in the imperial household after marriage.

The legislation has drawn sharp criticism from politicians and the public alike, however. The men considered candidates for adoption share a common ancestor with Emperor Naruhito from some 600 years ago, placing them 36 to 38 degrees of kinship from him.

Local media and opposition parties said the government had resorted to a contrived workaround by clinging to the patriarchal principle of male-line succession while sidelining Princess Aiko, who commands broad public support. Emperor Naruhito himself has reportedly expressed concern about the legislature's decision, saying on multiple recent occasions — both in private and in public — that "discussions should take place with broad public consensus."

The upper house plenary session on Friday also passed a bill creating a new offense of flag desecration, which has sparked debate over potential infringement of freedom of expression. Under the measure, anyone who intentionally destroys or defiles the Japanese national flag in a humiliating manner faces up to two years in prison or a fine of up to 200,000 yen ($1,230).

Also passed was an amendment to the Code of Criminal Procedure that would, as a general rule, bar prosecutors from appealing a decision to grant a retrial when decisive evidence of innocence emerges after a conviction has been finalized. Legal circles said the change resolves a long-standing grievance within the profession.