The ability to manipulate demons

Forty, the maid working for the Blanchar household has infiltrated a den of thieves.
After her master, the young lady Risette, was classified as a demon by the church,
she was abducted by a mysterious group of thieves…

The entire incident was seen as a means to let the demon escape and the head
of the Blanchar household was judged guilty of defying the church and executed.

The thieves that abducted Risette are still at large…
In order to save her master and prove the innocence of the Blanchar household,
the once upon a time assassin Forty…… takes up her blade once more.