Hikaru Gero is an assassin from a centuries-old clan of poison masters. Considering his less-than-honest occupation and complete lack of experience with women, he's never considered himself marriage material-that is, until the family orders his sister to produce the poison clan's next heir in his place. That's when Gero comes across his next target, Mei Kinosaki, a marriage swindler! Refusing to let his sister abandon her own chance at true love with her girlfriend, Gero enlists Kinosaki's services in matchmaking. Does Kinosaki have what it takes to turn this trained killer into a charming husband-to-be?