During the day, Miyazaki was a mild-mannered employee. In his own time, he selected children to kill randomly. He terrorized the families of his victims, sending them letters recalling in graphic detail what he had done to their children. To the family of victim Erika Nanba, Miyazaki sent a morbid postcard assembled using words cut out of magazines, spelling out: "Erika. Cold. Cough. Throat. Rest. Death."
He allowed the corpse of his first victim, Mari Konno, to decompose in the hills near his home, then chopped off the hands and feet, which he kept in his closet, and which were recovered upon his arrest. He charred the remaining bones in his furnace, ground them into powder, and sent them to her family in a box, along with several of her teeth, photos of her clothes, and a postcard reading: "Mari. Cremated. Bones. Investigate. Prove."
Police found that the families of the victims had something else in common: they had all been bothered by strange phone calls. The phone would ring, but when answered, the person on the other end (presumably Miyazaki) would say nothing; if they didn't pick it up, the phone would sometimes ring for 20 minutes.
In 1989, he became to be known as "The Otaku Murderer". His bizarre murders fueled a moral panic against Otaku. However, the reports of him were disputed. For example, Miyazaki was suspected to have many pornographic videos, but Eiji Otsuka suspected in his book that it was the forgery by a photographer, because people wanted to understand Miyazaki under their sense of values. On the other hand, Fumiya Icihashi suspected a part of stereotypes about Miyazaki as the information manipulation of the police because the police wanted to convict Miyazaki for the serial murders.
Following his son's arrest, Miyazaki's father, who had refused to pay for his legal defense, committed suicide in 1994.
He described his serial murders as a "good job" and had never apologized. Child killer Kaoru Kobayashi described himself as "the next Tsutomu Miyazaki or Mamoru Takuma. However, Miyazaki claimed that "I won't allow him to call himself 'the second Tsutomu Miyazaki' when he hasn't even undergone a psychiatric examination.
Kunio Hatoyama signed his death warrant and Miyazaki was executed by hanging on June 17, 2008. According to The New York Times, it was suspected that his execution was related with the Akihabara massacre. Japanese people suspected that because Miyazaki was a negative symbol of Otaku and Akihabara was a consecrated place of Otaku. However, the Ministry of Justice said, "We cannot answer. Ryuzo Saki said, "[H]is trial was long" and "I am not willing to criticize Hatoyama.
Wipo Publishes Patent of Toyama Chemical, Sahoe Kakuda, Tsutomu Miyazaki and Kotaro Okada for "Tablet Containing 1-Cyclopropyl-8-(Difluoromethoxy)-7-[(1R)-1-Methyl-2, 3-Dihydro-1h-Isoindole-5-Yl]-4-Oxo-1, 4-Dihydroquinoline-3-Carboxylic Acid Methanesulfonic Acid Hydrate" (Japanese Inventors)
Jun 07, 2013; GENEVA, June 7 -- Publication No. WO/2013/081044 was published on June 6.Title of the invention: "TABLET CONTAINING...