Tomioka Hachiman shrine in Tokyo was cordoned off Dec. 8 while police investigated a murder-suicide. (Yomiuri Shimbun/AP)

The attackers struck as the priestess stepped from her chauffeured car.

It was the night of Dec. 7 at the Tomioka Hachimangu, a centuries-old Shinto shrine in Tokyo famed for its annual festival and association with Japanese sumo wrestling. Nagako Tomioka, the chief priestess, was returning home to the tranquil grounds when a man hiding nearby charged at her wielding an 80-centimeter samurai katana-style sword, the Kyodo News reported.

He killed Tomioka while his accomplice, a woman, chased the driver as he fled on foot from the grounds. She caught up with him outside a nearby supermarket, where she delivered non-life-threatening injuries with a sword. Following the attacks, the katana-wielding man killed his accomplice before turning the sword on himself.

If the bloody murder-suicide at the shrine was not bizarre enough, the crime took an intriguing turn Friday, when police announced the alleged identity of the dead attackers: Shigenaga Tomioka, the priestess’s brother, was the killer, they said. His wife, Mariko, was the second assailant. According to authorities, the vicious attack was the climax of a long-building family feud over the leadership of the famous holy site.

“I was always worried that something like this might occur someday,” a woman who was a member of the shrine told the Asahi Shimbun last week. “But it is still a huge shock.”

The Tomioka Hachimangu dates to 1627, one of the 82,000 such sites scattered across Japan. The particular shrine was established for the worship of the god Hachiman, the god of martial arts and war, according to JapanVisitor.com. The shrine was the site of the first sumo wrestling matches in the 17th century, and today monuments are located on the wooded grounds. The shrine’s Fukagawa Hachiman festival, held every three years, is one of Tokyo’s major events.

According to Japan Times, the leadership of shrines traditionally passes from fathers to sons. Only 10 percent of the shrine priests are women, making Nagako Tomioka part of a very small minority. And the Tomioka family’s relationship to the Hachimangu shrine stretches back years.

The brother and sister’s father previously served as the chief priest, Kyodo News has reported. Shigenaga then took over for his father in 1995, but the son was fired from his position in 2001. The paper cites sources who said financial problems contributed to his dismissal. At the time, the father returned to work at the shrine, and Nagako Tomioka worked in the second-highest role at the holy site. In January 2002, Nagako Tomioka consulted with police over a family problem regarding the succession.

In 2006, Shigenaga Tomioka was arrested on a blackmailing charge, Kyodo News reported, for sending his sister a postcard promising: “I will send you to hell.”

The Japan Times reports the shrine came in conflict with the national association responsible for overseeing Shinto shrines in 2010 over the plan to place Nagako Tomioka in the chief priest position. According to the paper, the shrine left the group last September, and Nagako Tomioka became the chief priest not long after.

Her brother was reportedly still upset with Nagako Tomioka’s appointment. A shrine member told the Asahi Shimbun last week that in July he received a phone call from Shigenaga Tomioka complaining about her new role.

“He occasionally broke out crying or began shouting,” the member said. “I felt that he was emotionally unstable.”

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