The Holy Grail of Eris
Alternative title: Eris no Seiha, Eris no Seihai: Konyaku Haki Sareta Reijou ha, Kitai no Akujo, Tasukerareta Daishou Toshite Fukushuu ni Tsuki Awasaremasu, Eris no Seihai: Konyaku Haki Sareta Reijou wa, Kidai no Akujo ni Tasukerareta Daisho Toshite Fukushuu ni Tsuki, エリスの聖杯 ～婚約破棄された令嬢は、稀代の悪女に助けられた代償として復讐に付き合わされます～
Story Overview
Connie, who is the daughter of a Viscount whose only value is her honesty, and Scarlet Castiel, who was the most despised villain of the time and was executed ten years ago. The story that ought to have ended with Scarlet's death began anew when the two people who were never supposed to meet met at a night party. They only started dating because they were both interested in the same things, but they soon became real partners because they wanted to find out the truth about a huge conspiracy from the past that still has a bad hold on the present.