マリッジトキシン

Hikaru Gero was raised inside a centuries-old clan of poison assassins and takes it for granted that marriage is out of reach for someone from the underworld. When the clan demands an heir, it threatens to force his sister Akari, who has a girlfriend, into producing one instead. Gero answers by striking a deal with his latest target: Mei Kinosaki, a marriage swindler who lives as a woman and can make almost anyone fall in love. Kinosaki agrees to drill him through dating as a run of structured missions.