Back in Chapter 21, Tsukumo tells us that the police officer who gave him the blood sample was dressed in black, with silver hair, and glasses. When he turned around, he found the sample in the man's hand. He says that his blood is not enough to counter nine-tails terrorism, and that they have to figure out a way to transfer it to someone else. He tells us how happy he was when he found out that he had the blood, and how sorry he is that he has to throw his life away. He also says that he looks up to him, because people always force their own ideals on him. He adds that if he showed weakness, he'd get eaten, and he says that's why he's always smiling at him.