Her name is Jeanne Coulomb, the count's necromancer

Here is Jeanne Coulomb, the most powerful and strong-willed lady in the land! Lady Jeanne can see spirits. She was sent to a convent from the age of 10, because her mother did not like her outspokenness. One day, at the age of 16, she receives a letter from her sister Marise, the Countess, urging her to return home. What awaited Jeanne at the Coulomb house was a marriage proposal between Marise, who is haunted by spirits, and the Countess, who did not want to marry into such a dangerous situation. Jeanne makes an offer to Marise, “If I exorcise the spirits, you will withdraw the marriage proposal." What she then reveals is Marise's extraordinary secret... This is the start of a haunted comedy about the Lady Jeanne, who can control and subdue ghost and spirits! (Source: Kadokawa, translated)