Kizoku no Musume ni Tenseishita no ni Assassin no Maid ni Narimashita - Hayaku no Shibou Flag no You desu

"Do I really have to work here from now on...?" Maya Blanche was born the daughter of nobility, but the family's wealth is in ruins due to her father's loan. The only place she could find immediate work as a noblewoman was the most fearsome house in all the land, the San-Chevalier House. There are rumors of servants of the house going missing... as pain and fear comes over Maya, she suddenly feels a strong head pain and all her memories come flooding back to her. "In my previous life... I was a high school student!" Maya was reincarnated into the world of one of her favorite fantasy novels after an accident on her way home from her maid cafe job! She now remembers the head of the house, Etel San-Chevalier, is actually an assassin...! Now begins the story of an isekai love fantasy of excitement and wonder, avoiding the death flags at all costs! (Source: MangaPlaza)