March 1956, Tokyo. Private detective Reiji Tokisaka takes on a case from a girl in Inokashira Park who asks him to find her true self. Simultaneously, his childhood friend Sergeant Uozumi pulls him into a series of city murders. Then the vice principal of Oba Girls' Academy — where Tokisaka's own sister studies — asks him to investigate two recently vanished students. Tokisaka goes undercover as a teacher. On his first day, he meets the girl from the park again: Toko Kuchiki, calm and cryptic, who seems unsurprised to see him. As the body count rises and the missing persons numbers refuse to add up, a six-year-old unsolved case begins to look like the key to everything. Part I of a noir mystery visual novel.