マリッジトキシン (Series) favorite_border

Introduction to Volume 1: Gero is a young man who is a "poisoner," an assassin who has been in the business for hundreds of years. He is a backstabbing businessman who is not good with women, and marriage is something he should never have entered into. However, in order to keep the "poisoner" bloodline alive, his family forces his sister to give birth to an heir. Then Gero meets Kinosaki, a marriage swindler who was the target of his work...?　The marriage activity of a hit man with a marriage sw...