邪道堕ちる巫女 ～触手に敗北した姉妹～

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.