A 7 years girl is found dead in the local park’s toilet. Kaga Kyouichiro, who was asked to find the girl, and his cousin Matsumiya Shuhei who’s assigned to investigate the murder case, have to work together to crack the case. Their evidence lead them to Maehara’s, a family with parents, a son and a senile grandmother.

A man's body is found under the statue of a winged kirin in the Nihombashi area of Tokyo. A suspect named Yashima has a car accident and falls unconscious while he is attempting to run away. Yashima's lover Kaori comes from Fukushima and tells detectives that he is absolutely not a criminal. Meanwhile, Detective Kyoichiro Kaga's (Hiroshi Abe) investigates and uncovers a point of contact between the dead body and Yashima. A hidden fact of the victim is revealed which even his children did not know about...

A man is found dead in a office of Takayanagi Ballet Company. The suspect is a female dancer at the ballet company. The Takayanagi Ballet Company insists that the incident is a self defense case, but after an investigation there's doubts in that claim. Then, the director of the Takayanagi Ballet Company is poisoned to death. Are the cases related?

Michiko Oshitani, who lived in Shiga Prefecture, is found dead at an apartment in Tokyo. She was strangled to death. Mutsuo Koshikawa is the owner of the apartment and he goes missing. Detectives including Yuhei Matsumiya who is a cousin of Detective Kyoichiro Kaga , have difficulties in solving the case. They can't find a connection between Michiko Oshitani and Mutsuo Koshikawa. They soon learn that Michiko Oshitani came to Tokyo to visit Hiromi Asai . They graduated from the same school, but there isn't a connection between Hiromi Asai and Mutsuo Koshikawa. Detective Yuhei Matsumiya finds something near Michiko Oshitani's body. That something has the names of 12 bridges surrounding the Nihonbashi area of Tokyo. Detective Kyoichiro Kaga learns of the clue and becomes agitated. There's a connection with his late mother