Eiji Kirisame is a forty-year-old detective who has just met perhaps the oddest witness of his career: Tsugumi Kuchinashi, a silent high school girl who was present at a crime scene. Most of what she tells him comes as crude sketches on a drawing pad. Eiji is used to building the truth from scraps of evidence, so he gives every page careful attention in case it helps crack the case. Then he reaches the final page, which asks him to marry her. The result is a comedy mixed with mystery and romance.