Kyubi no Kitsune to Tobimaru (Sesshoseki) takes its inspiration from a novel by Okamoto Kidou and centers on a legend tied to a barren region at the base of Mt. Chausu, an active volcano in Tochigi Prefecture. Over the centuries, this area has gained notoriety for emitting hazardous gases like hydrogen sulfide, sulfur dioxide, and arsenic, which have killed animals and humans who came too near.
As legend has it, long ago in China, a kitsune assumed the form of a spellbinding woman, seduced the emperor, and brought disaster across the realm. She later traveled to Japan disguised as a beautiful woman named Tamamo, and likewise captivated the Japanese emperor. In time, her real identity was uncovered, and she was slain. In her dying breath, she placed a curse on those who killed her and became a poisonous stone called Sesshoseki, which is said to lie at that very location.