Death Loop Reijou wa Ikinokoru Tame ni Ryoute wo Chi ni Someru You desu

A girl named Hermina, daughter of Count Einhorn, becomes involved in a lethal game known as the "Summoning Ritual of a Wicked God" inside an old northern castle. She is joined by her childhood friend and maid, Charlotte, and seven others. Two of the participants are assigned as "demons," each responsible for killing one person each night. The remaining participants attempt to identify and eliminate the demons by voting to execute a suspect each day. No one can leave the castle until all demons are eliminated. Hermina must use her intelligence to survive and protect Charlotte.