"Aside from the arms shipment Nishida found? Drugs. It wasn't the witness selling drugs, it was the dirty cop. He was taking confiscated drugs and selling them for Takigawa. So he was worried that if his involvement with Takigawa and Nishida's death came to light, his drug dealing would also come to light, and his carefully constructed house of cards would collapse. And collapse it did."

Tatsuo struggles to keep the bitterness out of his voice.

"There was just one question left. If the witness didn't kill Takigawa, who did?"

Was. Because he recently learned the answer.