Saint-Saëns was a restless city under federal control, and a war transformed it beyond recognition. VICSON, the World Nuclear Weapons Research Institute, was hailed as a peacekeeper before the war, but after the war, it was labeled a war criminal, and most of its researchers were executed or exiled. And the fate of the two teenagers revolved around it... The famous Violet Agency was established after the war, and a group of young people existed to guard the peace of the city. As the case is solved, mysteries that have been hidden for many years are revealed one after another. The past that I don't want to remember, the soil under the dark night exudes the smell of rot...