Himitsu: The Top Secret Episode 4

3 people are murdered in quick succession. The Ninth begins investigating, believing the case to be one of serial murders. They link the case to one of the stabbing deaths of Satonaka Kyoko, a pharmacist murdered on the same train the victims rode. Just as Maki begins to believe the cases are related, another murder occurs. While looking at the 4th victim's brain, Aoki begins to believe all the murders are related. He notices that the victims have something wrong with them and asks Yukiko about it. But, then the body of one of the stabbing murder suspects is discovered... (Source: Japanese = ktv.jp || Translation = mikilove13 at kisskh)