Shoko Asahara
In 1988, Hirose read books written by Shoko Asahara by accident. He was attracted by Asahara and began to contact with Asahara. Per Asahara's request, in 1989, after graduating from graduate school and getting his master's degree, Hirose declined a job offered by NEC and joined Aum Shinrikyo, becoming an important person in this group. In the early 1990s, he produced around 1,000 assault rifles based on AK-74. It's reported that Hirose once went to Russia to test assault rifles produced by him.