Near the famous Nasu hot springs in Japan, there is a stone that is rumored to kill anyone who comes in contact with it.

In traditional Japanese culture, the kitsune or foxes are frequently depicted as mischievous spirits with shapeshifting powers. The most infamous of such creatures is Tamamo-no-Mae, who took the form of a beautiful woman to seduce the Emperor and become his mistress in the mid-12th century.

Legend has it that Tamamo-no-Mae's true identity was a nine-tailed fox, at least over 2,000 years old at the time. She had seduced several lords and kings prior to this, resulting in the collapse of the Shang dynasty and the deaths of 1,000 men in an ancient Indian kingdom called Magadha. After an onmyōji (mystic) exposed her identity, Tamamo-no-Mae was chased off and hunted down by a massive army, and finally defeated in the plains of Nasu by the heroic samurai Kazusa-no-suke Hirotsune.

But her story didn't end there. It is said that Tamamo-no-Mae's body transformed into a "murderous stone," whose powers took the lives of all those who approached it, humans and animals alike. Feared by locals, many Buddhist monks visited this Sesshōseki, or the Killing Stone, to calm the fox's vengeful presence, only to be killed by it. Finally in 1385, a monk named Gen'nō struck the stone, destroying it, scattering its pieces across Japan.

Several stones have been named Sesshōseki since then, but of course the one that can be found in Nasu is the original. It's still prohibited to approach the Killing Stone to this day... but not necessarily because of its legends.

The area is known for its volcanic presence, constantly producing poisonous gases, such as hydrogen sulfide and sulfur dioxide. This may be the origin of the myths of the Killing Stone, although one cannot wholly dismiss the legend. Nearby, there is a shrine dedicated to the Nine-tailed Fox, clearly part of the locals' attempt to appease the spirit of the beautiful, yet lethal, Tamamo-no-Mae.

Update: On March 5, 2022, Sesshōseki split in two, apparently from natural causes. Some believe that this may mean that the spirit of Tamamo no Mae has escaped her confinement.