Kiyohide Hayakawa, 51, got his master's degree at Osaka Prefectural University and started his career at a major general contractor. After changing jobs, he came across the books of guru Chizuo Matsumoto, also known as Shoko Asahara, and became a member of the Aum Supreme Truth cult. In 1987, after having actively participated in cult activities as the leader of its lay members, Hayakawa retired into the cult and donated his entire estate to it.
As a committed member, he made use of his expertise in building design to take charge of building cult facilities. He also spoke as the cult's representative at talks or negotiations with outside parties, as his social skills and initiative were highly esteemed within the cult. While most cult members were in their 20s, Hayakawa was six years the senior of Matsumoto. It was Hayakawa who visited The Mainichi Shimbun, whose weekly magazine, Sunday Mainichi, was running a series criticizing the cult. The cult intended to plant a bomb at the newspaper at a later date. He also visited TBS and demanded that the company not air an interview with lawyer Tsutsumi Sakamoto.
After the murder of Sakamoto and his family, Hayakawa often visited Russia to meet with politicians and other influential people in an attempt to expand the cult's influence.
He was also partly responsible for the militarization of the cult. He helped to purchase automatic rifles in Russia and a large helicopter from which the cult planned to disperse deadly sarin gas over a wide area. Given his devotion to cult activities, the prosecutors called Hayakawa Matsumoto's right-hand man and even his alter ego.
During his arraignment for the murder of the Sakamoto family, Hayakawa said, "I want to quit being a human," out of his unbearable sense of guilt. In the subsequent court hearings, he revealed his ambivalent feelings toward Matsumoto, saying "Asahara is a fanatic. As I believed he was the world's messiah, I, too, am a fanatic." However, he also said, "I cannot continue to live if I deny Asahara's spirituality," describing the complicated feeling within himself.
In the last session to hear his final opinions on the case held in March, Hayakawa apologized for his deeds. "All we (the cult) have done is to create a living hell," he said, adding "I am filled with remorse and shame for the fact that I still exist as a human (after all I have done)."