Crown Prince Akishino, the younger brother of Emperor Naruhito, has said he "approves" of his daughter Princess Mako marrying her university boyfriend, Kei Komuro, but reiterated that Komuro's mother must first solve an ongoing financial dispute.

"I mean, I approve of them getting married. The Constitution says marriage shall be based only on the mutual consent of both sexes. If that is what they really want, then I think that is something I need to respect as a parent," the crown prince told a news conference in Tokyo held ahead of his 55th birthday on Monday.

In a statement issued earlier this month, Princess Mako, 29, expressed strong resolve to go ahead with her marriage, which was originally scheduled in 2018 but pushed back following reports of a dispute between Komuro's mother and her former fiance over money, including educational expenses for her son that the man shouldered.