余命半年と告げられた令嬢は、醜い変人魔導士のもとへ姉の身代わりに婚約者として送りこまれました～楽しい余生を過ごしています

In the outstanding magical technology kingdom of Tilie, Fiene, the second daughter of the Hausen Earl’s family, was born without magical power, unlike the rest of her family. Because of this, she has been looked down upon not only by her siblings but also by her parents. She is considered a disgrace to the family, denied social interactions, and spends her days assisting her father with his work.

One day, Fiene’s health deteriorates, and she becomes bedridden. At first, her family and parents think she just wants attention or is trying to avoid work. However, Fiene eventually becomes unable to get out of bed, and when she finally consults a doctor, it is already too late—she is informed that she has only six months left to live.

On the other hand, due to her father’s investment failure, the Hausen family incurs massive debt. The parents ask their eldest daughter, Muge, to engage with a wealthy and eccentric magician living in the remote borderlands to alleviate their financial burden. However, Muge refuses, leading to a conflict with the third daughter, Maggie.

In the end, Muge and her brother devise a plan. They make Fiene her sister’s substitute and send her to the remote territory where the eccentric magician resides, believing that Fiene has little time left anyway. Contrary to her initial expectations of revenge, Fiene discovers that the magician is a kind person. Thus begins Fiene’s leisurely and happy, slow life.