A Japanese 'killing stone,' said to contain an evil 9-tailed fox spirit, has split in two

A killing stone cracked in half in Nikko National Park, Japan, supposedly releasing an evil nine-tailed fox spirit.

(CNN)An evil fox spirit is on the loose after breaking free from her rock prison -- that is, if you believe in Japanese mythology.

A Sessho-seki, or "killing stone," was found cracked in half this month in Nikko National Park, about 100 miles (160 kilometers) north of Tokyo.
No one knows exactly what caused the stone to crack, but the cold winter months could have contributed to the cracking, said Nick Kapur, an associate professor of history at Rutgers University in Camden, New Jersey.
    The killing stone remained in one piece for nearly 900 years before splitting open earlier this month.
    Each winter, water could have seeped into the crack, frozen, then expanded, he said. However, many look for guidance from the myth, he added.
      There are multiple versions of the legend, but it was believed Tamamo-no-Mae, a nine-tailed fox spirit, lay trapped in the rock for nearly 900 years.
      The tales all center around retired Emperor Toba, who reigned in Japan from 1107 to 1123.
      Tamamo-no-Mae was known for her shape-shifting abilities, so she transformed herself into a beautiful woman and caught the eye of the emperor, Kapur said.
        As she grew closer to the emperor, he fell gravely ill, Kapur said. A court astrologer used divination to determine Tamamo-no-Mae was the culprit, he said.
        Once her plan was foiled, she fled into the wilderness, changing shapes to try and stay hidden, he said. However, samurai sent after her eventually caught up to the fox spirit, Kapur said.
        When one of the warriors shot her with an arrow, her physical form was killed, so her spirit transformed into a stone, he said.
        Legend goes that if you touch the stone, you die, hence the name killing stone, Kapur said.
        There is no proof of the stone's supernatural abilities, but its unique location may have given substance to the rumors, said Yoshiko Okuyama, professor of Japanese studies at the University of Hawaiʻi at Hilo.
        The stone is near multiple volcanoes, so occasional gases that were released may have killed some animals or humans over the years, she said.

        A spirit with a change of heart

        The rock has become a top tourism site and skyrocketed in popularity, but it paled in comparison to the spirit's fame, Okuyama said.
        The fox spirit has made numerous appearances in modern Japanese media, often as the villain-turned-hero character, she said.
        "More recent adaptations in manga and anime don't want to portray women in a misogynistic way," Okuyama said.
        In older Japanese myths, the stories centered around evil female spirits out to undermine the power of males, Kapur said.

        An omen for our time

        After the stone cracked, people were quick to chime in on the timing of the breakage.