Prince Akishino, the younger son of Emperor Akihito, has questioned whether the state should finance one of the Shinto-linked rituals to be held following the Imperial succession.

The prince, speaking at a news conference held before his 53rd birthday Friday, also had a message for Kei Komuro, the boyfriend of his daughter, Princess Mako. The prince urged Komuro — whose mother is involved in a dispute with her former fiance over money spent on Komuro’s education — to deal appropriately with the issue if he wants to marry her.

Prince Akishino will be promoted to first in line to the throne after the enthronement of his brother, Crown Prince Naruhito, on May 1, 2019.

He expressed doubts at the news conference about the constitutionality of the Daijosai grand thanksgiving rite to be held in November next year, saying he believes it is a “highly religious” event.

The supreme law bans the state from engaging in religious activities. Shinto is Japan’s indigenous religion, in which the Emperor is venerated as a descendant of the sun goddess.

“I wonder whether it is appropriate to cover the highly religious event with state funds,” the prince said, adding that he believes the ritual should be paid for with money used to fund the Emperor’s private expenses.

The prince said he was also opposed to using public funds the last time the rite was held, in 1990, a year after his father ascended the throne in 1989.

Although the ceremony will be treated as an Imperial event — not as a state occasion — critics claim it will threaten the separation of religion and state if public funds are used.

The prince said he has conveyed his views to the chief of the Imperial Household Agency but that the government has already decided to use public funds for the ceremonies in line with the succession rites for Emperor Akihito.

The prince said he felt regret that “the agency did not listen to me.”

In response, the agency’s Grand Steward, Shinichiro Yamamoto, said it was “painful” to hear the prince’s remarks and that he was sorry if his attitude was misunderstood.

But Yamamoto added: “As the previous Daijosai (funded by public money) was held with public support, it is reasonable to follow the precedent.”

The Daijosai is the name given to the first annual Niinamesai harvest festival to be performed by a new Emperor and always follows an accession to the throne.

In the rite, to be held from Nov. 14 to 15, the new Emperor will offer new rice to the Imperial ancestors and to the Tenjin Chigi, the deities of heaven and earth, while praying for peace and abundant harvests for the country and the people.

Although annual Niinamesai rituals are covered by the Emperor’s personal expenses, the Daijosai will be financed with public “palace-related expenses” used for the Imperial family’s official duties such as ceremonies and state banquets

In relation to the previous Daijosai in November 1990, which cost about ¥2.2 billion ($19 million), a number of lawsuits contesting its constitutionality were filed across Japan, but they were all dismissed.

But a 1995 ruling by the Osaka High Court noted that doubts remain over whether the government financing of Shinto-linked rituals breaches the Constitution.

Prior to the upcoming Daijosai, at least 120 people, including Christian and Buddhist followers, are planning to file a lawsuit with the Tokyo District Court — possibly in early December — in a bid to block the state funding of the rite, according to their representatives.

On his daughter’s engagement, the prince said Komuro “has to solve the problems that have surfaced. If (their marriage) cannot be celebrated by many people, we cannot hold the betrothal ceremony of Nosai no Gi,” which was originally scheduled to take place on March 4 this year.

The agency announced in September last year that a wedding between Princess Mako and Komuro, both 27, would take place on Nov. 4, 2018. But the agency said in February that the couple will push back the schedule until 2020 following a string of reports that Komuro’s mother is in a dispute over money with her former fiance over her son’s educational expenses, which the ex-fiance shouldered.

In August, Komuro, a paralegal at a Tokyo law firm, started a three-year course at Fordham University’s law school in New York, aiming to pass the state’s bar examination.

The Imperial succession slated for next year comes after the 84-year-old Emperor expressed his desire to step down due to his advanced age and failing health. Following the abdication of the Emperor on April 30, 2019, Prince Akishino will be given the title kōshi — first in line to the throne.