Yui is a shrine maiden at Tokutari Shrine. She was originally a female monster, but hundreds of years ago her magical power was sealed by Tokumaro, an onmyoji and former head priest of the shrine. Now she works peacefully as a shrine maiden, but whenever demons appear from the netherworld, she becomes a demon hunter to protect the humans. One day, Yui tells her students about the local legend of the earth spider (Tsuchigumo). However, the students’ teacher, Miyako Otoha, appears and punishes the students. In the process, she accidentally destroys the stone monument that seals the Tsuchigumo demon. Freed from its seal, the demon possesses Miyako and attacks Yui. Now, Yui must face the centuries-old grudge of the Tsuchigumo demon and confront the danger threatening everyone.