四ノ宮小唄はまだ死ねない　ーＢＯＲＤＥＲ　ＯＦ　ＴＨＥ　ＤＥＡＤ－

10 years ago, around 7.6% of the human population was afflicted with a new disease that changed them into the dead. That disease was nicknamed "border." Though they were still living, they were objectively corpses. In a world where the boundary between life and death is shaking, a high school detective and a girl afflicted with border face work together.