A murder mystery told in one-minute clips — one for each day of the year — filmed specifically for the SEGA Dreamcast console. It tells the story of Nao Tsunoda, a 16-year-old schoolgirl who moves to Tokyo’s Grauenheim apartment complex. One day, Nao’s life turns into a nightmare when she suddenly discovers the headless corpse of her neighbor on the roof of the house — and a chain of brutal murders continues, becoming clear that a psychopath is hunting the apartment building's inhabitants.