The Paper is the codename bestowed on the resident Papermaster of the Special Operations Division. There is a long line of paper masters, and succession appears to pass down on a teacher-student basis.
Donny Nakajima was the eighteenth Paper Master and considered one of the best. He trained Yomiko Readman and after his death Yomiko assumed the title of The Paper. She is the 19th. It is unknown if any succeeded her as the 20th.