Public Prosecutor Zen Seizaki, investigates the "Agras" case alleging that the Japan Supiri pharmaceutical company is promoting a defective drug. There are allegations that four universities have provided falsified test results. During the investigation, he finds a sealed document in a file which includes blood stains, hair, skin, fingernails and the letter "F" is written repeatedly on the paper. The material is traced to the anesthetist Shin Inaba, but when they go to his apartment, they find him dead from an apparent anesthetic overdose...