After studying martial arts, yoga, and Agon Shu, in 1986, when he was a sophomore in high school, he attended the Aum Shinzen no Kai's Tanzawa Seminar.
[7] In February 1988, he appeared with Aum members in NHK's "Ohayo Journal" ("Mysterious" Young People in the Midst of Changing Religious Consciousness).
[9][7] Eventually, under Asahara's direction, he dropped out of college in the first semester of his freshman year and became a Buddhist priest, and his mother also became an Aum lay follower.
He was also involved in the Shinjuku Station cyanide gas incident and the Tokyo Metropolitan Government parcel bombing as the ringleader.
During the trial, he showed remorse for the Aum Affair, but he tended to trivialize and shift the blame by claiming that he was not heavily used, which raised questions about the credibility of his testimony.
This was the first time in the Aum Shinrikyo case that a sentence of life imprisonment was handed down in response to a request for the death penalty.
Moreover, Tomomitsu Niimi also began to testify that Inoue was in a very important position in the sarin gas incident, and that he was happy immediately after the bombing of Shimada Yumi's house, saying, "I did it!
[18] On May 28, 2004, the Tokyo High Court upheld his conviction for the arrest and confinement manslaughter in the Meguro notary public office case, and found that he played an important role in the indiscriminate mass murder of people as a general coordinator, although he was not the on-site commander of the sarin gas attack.
The letter stated that the cause of the chief's death was a side effect of anesthesia, which was not true, and that Tomomasa Nakagawa (a doctor at the time) may have intentionally killed him.
[22] In the first trial of Katsuya Takahashi, he was charged with manslaughter by arrest and confinement, and the defense disputed the cause of death of the office manager, so a detailed hearing was held on this issue.
On June 30, 2014, the Tokyo District Court ruled that Inoue's testimony was credible and that it was based on the fact that he was aware that Kikuchi was going to commit the crime.
Later, the Tokyo High Court of the second instance, in its judgment on November 27, 2015, stated that Inoue's testimony was "unnaturally detailed and specific, while many people's memories of that time are vague," and that its credibility should be carefully judged.
According to the results of the fact-finding investigation in the second trial, Inoue and others were found to have concealed the purpose of their activities from two female believers who had been coming and going to the room in question (the hiding place in Hachioji City) in other important roles, and Kikuchi was only an assistant of Masami Tsuchiya in the Kushitigarbha building, not a subordinate of Inoue, and was in the position of assistant master, two levels above ordinary believers in the cult.
After his acquittal and release, Kikuchi wrote an article titled "Yoshihiro Inoue's Lies (1) to (5)" in his blog, "Because the Deeper the Darkness, the More Stars You See.
[28] Until March 14, 2018, all 13 death row inmates in the Aum Shinrikyo case, including Inoue, were incarcerated at the Tokyo Detention House.
[29][30] However, in January 2018, the criminal trial of the Aum Affair was concluded with the confirmation of Katsuya Takahashi's life imprisonment, and on March 14 of the same year, seven of the 12 death row inmates, excluding Shoko Asahara, were transferred to five other correctional facilities with execution chambers.
[31] On March 15, 2018, the day after the transfer, he filed a request for a retrial with the Tokyo High Court, saying, "I want to make it clear that the facts are different, not to avoid the death penalty.