Police officer Ohno Makoto discovers a lady covered in blood at Shinobazu Pond in Ueno. Feeling sorry for her, he gives her the temporary name "Koike Shinobu" and lets her live at the tofu shop run by his parents. Even though she has not regained her memory, Makoto is gradually drawn to Shinobu's brave personality. At that time, a mysterious man named Yamane began to appear around Shinobu. Yamane is actually a detective who is pursuing the culprit of a murder that occurred in Nagano. The victim was Shinobu's father, and Shinobu's stepmother has already been arrested, but Yamane is convinced that Shinobu is the real culprit and targets her. Makoto takes Shinobu on a journey to find the real culprit.