The woman was ambushed by a man and a woman wielding samurai-style swords as she was leaving her car. Her driver was also attacked by non-life threatening injuries. The attackers have turned out to be her brother, Shigenaga Tomioka, and his wife. Shigenaga killed his sister then murdered his wife, before committing suicide.
In a case of bitter irony, the Shinto shrine, one of 82,000 sites around Japan, was established in the 17th century to worship the god Hachiman, the god of martial arts and war.
What was the motive? A long-standing family feud about control of the shrine. Female priests are rare in Japan. Only about 10% of the Shinto shrines have female priests. Usually, the priesthood is passed from father to son. Shigenaga was originally the head priest of the shrine but was fired in 2001, possibly for financial difficulties. The feud was extreme enough that Shigenaga had sent death threats to his sister and Nagako had sought help from the police.
The Tomioka Hacimangu shrine is a considerably famous Shinto shrine, with a long-standing connection to the family. It is closely linked to sumo wrestling and has been recently visited by the royal family.
It is unclear if there was a recent event that caused the attack and if suicide was part of the plan. It was clearly planned out given that the assailants had been laying in wait for the victim.
There has not been a statement from the site nor the family.