Sadako Yamamura
is a major character in the series, first appearing in "Ring". In "Ring", Ryūji Takayama is a strange man with a dark sense of humor, who as such claims to be an occasional rapist and seems to fear nothing. As soon as Asakawa explains the story, Ryuji believes him, and wants nothing other than to see the cursed videotape. Asakawa shows it to him, and although Ryuji remains nonchalant, he agrees there is a powerful aura around the tape. He asks Asakawa to make him a copy to study at home, which Asakawa does. By the end, he and Asakawa believe they have solved the mystery surrounding the series' central character, Sadako Yamamura; the following day, however, Sadako's malignant spirit emerges from the tape and kills him. In "Spiral" a former medical school classmate, Ando, performs the autopsy on Ryuji. He discovers a bit of newspaper sticking out of Ryuji's stomach sutures, with two sets of numbers on it: "178" and "136". Later on, it is traced to a code, utilizing a sequence of Ryuji's DNA. The message contained was "mutation". Ando later discovers that Ryuji decided to join forces with Sadako, and is blackmailed by Sadako into bringing Ryuji back to life. Sadako and Ryuji then plot to spread the virus throughout the world using the diary of his dead friend, Asakawa.