Seijo-sama o Osagashi Deshitara Imouto de Machigai Arimasen. Saa, Douzo Otsure Kudasai, Ima Sugu. - Ch. 1

[MangaDex]

 

[FloorRoof]

At first I thought this would be a comedy series about trying to get rid of an overly charitable pest of a sister, but after the other part of chapter it looks a lot like one of those stories about an impoverished saintess who's abused by her fake-saintess sister.