Kenichi Hirose was born on June 12, 1964, in Japan. From an early age, he stood out as an exceptional student. Teachers and peers recognized him as both quiet and highly intelligent. He excelled academically throughout his youth, eventually earning admission in 1983 to Waseda University, one of Japan’s most prestigious institutions. There he majored in applied physics, a field requiring rigorous study and high aptitude.

In 1987, Hirose graduated from Waseda as the top student in his class. His brilliance earned him a place in the university’s Graduate School, where he researched high-temperature superconductivity. He co-authored and published a paper in July 1987, impressing his professors, one of whom later described him as a gifted scientist with great potential. Despite his academic success, Hirose felt uncertain about whether his knowledge and research could benefit society in a meaningful way. This philosophical questioning would later make him vulnerable to Aum Shinrikyo’s ideology.

In 1988, Hirose came across writings by Shoko Asahara, the charismatic leader of Aum Shinrikyo. Intrigued, he began corresponding with Asahara, who persuaded him to abandon conventional life. In 1989, after completing his master’s degree, Hirose rejected a lucrative job offer from NEC and instead joined the cult. This marked a dramatic shift from a promising scientific career to a path of extremism.

Within Aum Shinrikyo, Hirose quickly became valued for his technical expertise. By the early 1990s, he was leading the cult’s secret weapons program, producing around 1,000 assault rifles modeled after the Soviet-designed AK-74. Reports suggest that he traveled to Russia to test these weapons.

By 1995, Aum Shinrikyo was preparing to launch a large-scale terrorist attack on Tokyo. Shoko Asahara and his inner circle believed violence was necessary to accelerate the apocalypse they preached. Hirose, now fully entrenched in the cult, was assigned a deadly mission: to release sarin, a highly lethal nerve gas, on a crowded commuter train.

On the morning of March 20, 1995, Hirose boarded train A777 on Tokyo’s Marunouchi Line. Carrying liquid sarin concealed in a plastic bag and wrapped in newspaper, he punctured the package with the sharpened tip of an umbrella. Poisonous fumes began spreading rapidly inside the train. Passengers soon collapsed, gasping for air, while chaos engulfed Tokyo’s subway system.

The coordinated attacks across multiple subway lines killed 13 people and injured more than 5,000, making it the deadliest terrorist act in Japan’s history. Hirose was arrested later that year alongside other senior Aum Shinrikyo members. His role in both weapons manufacturing and the gas release made him one of the cult’s most significant operatives.

In 2000, Hirose was sentenced to death for his participation in the attack and the deaths it caused. He appealed the ruling, but in 2006, his final appeal was dismissed. For more than a decade, he remained on death row in Japan, awaiting execution.

On July 26, 2018, Hirose was executed by hanging at the Tokyo Detention House, alongside several other Aum Shinrikyo members.