In 1988, Hirose read books written by
Shoko Asahara by accident. He was attracted by Asahara and began to correspond 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 the
AK-74. It was reported that Hirose once went to
Russia to test these rifles. ==Tokyo subway gas attack, arrest, trial and execution==