Shijou Saikyou no Mamahaha ni Hyoui Shimashita

Chitose wakes one morning inhabiting the body of Claire, a novel's antagonist known as the most fearsome woman ever to live. Claire was married off to Duke Vermillion, the man called the Grim Reaper of the Battlefield, and the plot condemns her to execution. Bewildered, Chitose then meets three small children who appeared nowhere in the book. She adores children and once trained toward nursery teaching, but they are frightened of her, and the duke home from war shows no warmth toward wife or children alike.