Why Princess Aiko Cannot Become Emperor of Japan

 
37 years after the death of Emperor Showa, Japan is once again embroiled in royal succession debates, this time concerning the future of the imperial line. The focus is on the issue of whether Princess Aiko, the only daughter of the current Emperor Naruhito, should be granted succession rights. However, this topic has been notably absent from recent discussions regarding reforms to the imperial family system.
 
The Japanese government has proposed measures that would allow married female royals to remain in the imperial family and perform official duties, as well as adopt male descendants from former royal families to maintain the dwindling number of royals. Yet, the question of allowing a female emperor or granting succession rights to Princess Aiko has been excluded from these discussions.
 
This has led to public frustration, with some questioning, "Why are we looking for male descendants from former royal families that separated centuries ago while leaving Princess Aiko aside?" This sentiment resonates with many, including those in South Korea.
 
To understand this issue, it is essential to differentiate between two terms frequently used in Japan: 'female emperor' and 'female succession.' While they may seem similar, they represent distinct concepts. A female emperor refers to a woman ascending to the throne, which has historical precedent in Japan, with eight female emperors having reigned in the past.
 
However, the conservative political factions in Japan prioritize 'female succession,' which pertains to the lineage of the imperial family rather than the gender of the successor. For instance, if Princess Aiko were to become empress and her son were to inherit the throne, he would be considered a product of 'female succession' because he would inherit the imperial bloodline through his mother. Conversely, if a male emperor were succeeded by a male heir from the same male lineage, it would not be classified as 'female succession.'
 
Thus, the principle that conservatives seek to uphold is not merely that only men can be emperors, but that the imperial bloodline must be passed down through the male line.
 
This distinction sheds light on why the Japanese government prioritizes male descendants from former royal families over Princess Aiko. While the public may view the current emperor's only daughter as a more relevant candidate, the political landscape values the continuity of bloodlines over individual candidates.
 
Public opinion appears to diverge from political tradition. Recent surveys indicate that around 70% of Japanese citizens support the idea of allowing a female emperor, and many do not oppose the prospect of Princess Aiko becoming the next empress. Conversely, there is significant opposition to the idea of reinstating male descendants from former royal families, highlighting a growing gap between traditional political views and public sentiment.
 
Globally, royal succession practices are evolving. In 2013, the United Kingdom amended its succession laws to eliminate gender distinctions, allowing the firstborn child, regardless of gender, to inherit the throne. Sweden was the first to implement gender-neutral primogeniture in 1980, with other countries like the Netherlands, Belgium, Norway, and Denmark following suit. Today, many European monarchies prioritize birth order over gender.
 
Internationally, the United Nations Committee on the Elimination of Discrimination against Women (CEDAW) has repeatedly urged Japan to reconsider its male-centric succession laws, citing gender equality principles.
 
However, the Japanese government has rejected these recommendations, asserting that succession is a matter of national history and tradition, not gender equality, and has taken a firm stance against CEDAW, even withholding some contributions.
 
Interestingly, many historians do not view the current male succession principle as an unchangeable tradition. Research indicates that female emperors existed, and the strict male-centric system was solidified during the Meiji era.
 
In 1989, I witnessed Japan halt broadcasts in mourning for Emperor Showa. In 2026, the majority of the public supports Princess Aiko as the next empress, yet the political establishment remains reluctant to abandon the male succession principle. While the emperor may change, the surrounding institutions are slow to adapt.
 
This royal succession debate is not merely about who will become the next emperor; it serves as a litmus test for how far Japan is willing to uphold tradition while adapting to contemporary societal changes.