TOKYO — Princess Aiko of Japan celebrated her 23rd birthday on Sunday, assuming an increasing number of official responsibilities while uncertainty looms over her prospects within the imperial lineage.

Aiko, the sole offspring of Emperor Naruhito and Empress Masako, recently completed her university education. Following her graduation earlier this year, she has been actively engaged in ceremonial duties and palace traditions, in addition to her involvement with the Red Cross Society, as reported by the Imperial Household Agency.

However, Japanese legislation necessitates that she relinquish her royal title and exit the imperial family should she choose to marry someone outside of the royal circle.

The vast majority of the Japanese public is in favor of reforming the law to enable Aiko to maintain her royal status and potentially ascend to the throne. Nonetheless, conservative factions within the ruling political party are adamant about preserving the male-only line of succession. Currently, the imperial family comprises only 16 members, of which four are male, presenting a challenge for a family that has lasted over two millennia.

Aiko celebrated her birthday in the presence of her parents at the imperial palace in Tokyo. The Imperial Household Agency also shared various images of the princess, one depicting her beside a persimmon tree in the palace garden, while another showcased her crafting traditional washi paper during her inaugural solo official trip to the National Sports Festival in Saga Prefecture last month.

The 1947 Imperial House Law, which reflects conservative values from the pre-war era, restricts the throne to male successors and requires female members who marry outsiders to forfeit their royal privilege. This has led to concerns regarding the future of the monarchy, particularly given that there is only one young male royal.

Prince Hisahito, Aiko’s 18-year-old cousin, currently stands as the last male heir apparent, which complicates the succession issue significantly. The government is exploring strategies to ensure stable succession without depending on female royals, including the possibility of adopting male heirs from former noble families that lost their status post-World War II.

Aiko’s personal opinions regarding these matters remain largely undisclosed, having only held one comprehensive press conference when she transitioned into adulthood.

In a recent report issued by the United Nations women’s rights committee in Geneva, calls were made for the Japanese government to permit a female emperor, alongside other recommendations aimed at enhancing gender equality within the nation.

Chief Cabinet Secretary Yoshimasa Hayashi responded to the report, labeling it as “regrettable” and “inappropriate,” asserting that imperial succession ties deeply into national identity and should not be considered within the framework of basic constitutional rights.

Crown Prince Akishino, Aiko’s uncle, addressed inquiries regarding the succession debate during his 59th birthday news conference, stating that members of the royal family are “living humans” and that those supporting their daily activities ought to comprehend the implications of these issues.

At the Japanese Red Cross Society, Aiko is involved in a volunteer training program, as noted by the Imperial Household Agency. During her weekends, the princess enjoys leisurely walks with her parents and participates in sports such as volleyball, tennis, and badminton with palace staff.