The Bungetsu family has been exterminating demons for generations.
The elder sister, Hanabo, and younger sister, Harlan, are priestesses who were born into the family.

One day, they learn that the seal of an evil god has been broken.
Hanaoka tries to exterminate it.
However, she is captured by the evil god’s tentacles and turned into his servant.

Swearing allegiance to the evil god, “Hana-ho” returns to Bungetsu’s house and takes her beloved sister to the evil god’s house.
She leads her beloved sister to the Evil God. ……