Through the city of Sendai runs the Hirose River. It has several stream pools along its course, one of which is known as Kashikobuchi, or the Wise Abyss, and there is a chilling legend that accounts for its name.

Once upon a time, a local man was fishing by this stream pool when he found a gossamer thread tied around his ankle. Finding it strange, the man undid it and instead tied it around the trunk of a nearby willow tree. The same thing happened over and over again, until the tree got dragged into the water with a loud noise. Dumbfounded, the man stood there watching the ripples spread on the surface of the river.

Out of the silence that followed, an ominous voice was heard saying “Kashikoi, kashikoi  (Very wise, very wise).” Then the man finally saw what lurked underneath the water: a monstrous spider that reigned over the area, an ancient eldritch creature preying on unsuspecting villagers.

Interestingly, the same spider makes an appearance in another folk tale of Sendai. In this legend, a large eel that lived in the downstream called on another villager to aid him in a fight with the spider, asking him to stand by as a witness and not to make a sound. The next evening, the villager came to see the eel and the spider fighting, and could not help but scream in terror. This caused the eel to lose the battle, and all the villager saw the moment before he lost his mind and died was its severed head glaring grudgingly at him from the water.

The Spider of Kashikobuchi was both feared and worshipped by the villagers, who regarded him as a god of trade and protector against floods. Today, a largely neglected stele in the thicket by National Route 48—overlooking the Kashikobuchi pool, no less—serves as the only testament to this spider god, here referred to as Myōhō-gumo-no-rei, or the Ghost of the Mystic Spider.