A group of western Japan citizens sued the Kyoto governor on Wednesday for the return of taxpayers' money used for him and other prefectural officials to attend a Shinto ceremony last year to mark Emperor Naruhito's enthronement, arguing their attendance violated the Constitution.

The plaintiffs claim Gov. Takatoshi Nishiwaki should return around 390,000 yen ($3,700) as his actions ran counter to the constitutional principle of separation of religion and state when he attended the Daijosai, a centuries-old overnight Shinto thanksgiving ceremony, held in November last year at the Imperial Palace in Tokyo.

Photo shows the Daijokyu Halls on the Imperial Palace grounds in Tokyo in the early hours of Nov. 15, 2019, after the "Daijokyu no gi" main rite of the Daijosai great thanksgiving ceremony performed by Emperor Naruhito. The Daijosai is a key rite performed by a new emperor once during his reign. (Kyodo) ==Kyodo

In the suit filed with the Kyoto District Court, the 12 Kyoto residents also raise questions about the attendance by the governor and prefectural officials at a ceremony related to the Daijosai held in Nantan in the prefecture in September last year.

"It clearly violates the principle of separation between religion and state for the governor and other local government officials to be involved in religious ceremonies and for their expenses to be covered by taxpayers' money," the plaintiffs said in the suit.

Nishiwaki and the other officials joined Daijokyu no gi, the main part of the Daijosai, in which the emperor offered newly harvested rice to the Shinto sun goddess Amaterasu as well as the deities of heaven and earth on Nov. 14 and 15 last year.

They also took part in Saiden Nukiho no gi, a ceremony to harvest the new rice used in the Shinto ceremony, held in Nantan. The Daijosai was the last of the major succession rituals following the emperor's enthronement in May last year, but the state-funded secretive rite stirred controversy for its religious aspect.

The plaintiffs and some others filed a resident audit request in August, demanding the prefectural government's audit committee urge the governor to return the money spent in relation to the Daijosai based on the same reason, but it was turned down in October.

Rice cultivated in Kyoto Prefecture was used in the Daijosai, representing the western part of the country, while rice grown in Tochigi was chosen from eastern Japan.

Emperor Naruhito ascended to the Chrysanthemum Throne on May 1 last year following his father's abdication.

Similar concerns were raised for the previous Daijosai ceremony performed by former Emperor Akihito in 1990, the first such ritual under Japan's postwar Constitution.

An Osaka High Court ruling in 1995 said doubts remain whether government financing of Shinto-linked rituals breaches the Constitution.

But the central government has maintained the public nature of the ceremony held to mark the imperial succession warrants it being state-financed.

Japanese Emperor Naruhito (R) clad in white traditional attire heads to the Suki Hall, part of the gigantic Daijokyu Halls, to perform the "Daijokyu no gi" main rite of the Daijosai great thanksgiving ceremony on the Imperial Palace grounds in Tokyo on Nov. 15, 2019. (Kyodo) ==Kyodo