Hadaka no jûkyû-sai

After leaving high school, Michio Yamada (Norio Nagayama in the real life incidents) becomes involved in the shudan shushoku, a post-war Japanese government work program which involves taking almost an entire high school graduating class from the countryside to Tokyo to work for a fruit company. Some terrible things happened to his family in the past and that explains why Michio came later to have perpetrated so many killings.