Puzzled as the tumor appears similar to smallpox (which was eradicated in 1979), Ando completes the autopsy and, upon finding a newspaper poking through a suture, is reminded of Ryūji's cryptography hobby.
Despite dismissing the documents as pseudoscientific, Ando and Miyashita continue reading and discover that the Ring Virus started with the murder of psychic Sadako Yamamura.
Additionally, despite having given no physical indication that she was pregnant, Mai's corpse shows signs that she gave birth prior to her death.
Upon visiting the crime scene, Ando meets a beautiful woman named Masako who introduces herself as Mai's older sister.
Believing that Masako is Sadako reborn, Ando receives a note from her explaining that Mai was infected with the 2nd "sperm" ring virus which targeted her womb.
By supernaturally causing the paper code to appear to Ando and making Mai watch the tape when she was most fertile, Ryūji was the mastermind behind the plan, doing so to be spared and revived by Sadako.