Origin
When his little sister Chisel was sick he worked for Cavanaugh. He assassinated people with rare guns for medicine to cure his sister. Unknowingly the medicine he gave her did not cure her. It was narcotic which slowly killed her. The Cavanaugh gave him drug just to make Chisel a guinea pig. He wanted revenge so he seek the Eto gun in order to end the syndicate. Seeing Mingchao reminds him of his sister.