According to Japanese beliefs, Furuutsubo are the beloved quivers of slain archers who died particularly tragic deaths. These quivers — along with other arms and armor — develop life force due to the residual energies left behind by their owners. They begin to move around on their own.

The most famous furuutsubo was the quiver which belonged to Miura Yoshiaki, a military commander who lived at the end of the Heian period. Yoshiaki was a brave warrior, skilled in sword and bow. For the Genpei War (a national civil war between the Taira and Minamoto clans during the late-Heian period of Japan, 1180-1185), he fought on the side of the Minamoto clan. As the enemy was bearing down during a terrible siege, Yoshiaki arranged for his household to escape from the castle. Then, as the last few survivors made it out safely, he remained alone. Yoshiaki stayed behind to defend the castle against the invading army. He sacrificed his life. After his heroic death, his favorite quiver was heartbroken at the loss of its master. It took on a life of its own and became this yōkai-tsukumogami.