Osan Gitsune is a Japanese Yokai monster folklore in the West especially Shikoku area.
It is a beautiful woman that a fox transformed. It tries to attract men especially who has a partner. In Japan, a woman who is cheating, or disturbing one's relationship is called "female fox". The word came from this yokai.
In Tottori Prefecture, there was Osan Gitsune living in a place called Garagara. A young man Taniguchi Sohei was nearly tricked by this Osan Gitsune. Then Sohei lit a fire and threated the fox. The fox promised that it'll never happen again, then Sohei let the fox go. Some years later when people from the same village as Sohei's went to Iga. They saw a young girl who asked them about how Sohei is doing. The villagers answered he's doing ok. The young girl said "Fearful!" and ran away.
In Hiroshima City, Osan Gitsune used to transform into fire or lion to scare people. A hunter captured the fox to kill, the fox begged the hunter saying "If you let me go, I'll transform into Daimyo marching tomorrow night". The hunter let the fox go. The hunter saw a daimyo marching next night, and he praised the fox. However, it wasn't fox. It was an actual daimyo marching. So the hunter was executed because of his disrespecting attitude.