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Sarin gas attack on the Tokyo subway

Sarin gas attack on the Tokyo subway
Location Tokyo, Japan
Target(s) Tokyo Metro
Date March 20 1995
7:00-8:10 (UTC+ 9)
Attack type Chemical
Deaths 12
Injured 1,034 (50 severe; 984 temporary vision problems)
Perpetrator(s) Aum Shinrikyo

  The Sarin gas attack on the Tokyo subway, usually referred to in the Japanese media as the Subway Sarin Incident (地下鉄サリン事件 Chikatetsu Sarin Jiken?), was an act of domestic terrorism perpetrated by members of Aum Shinrikyo on March 20, 1995.

In five coordinated attacks, the perpetrators released sarin gas on several lines of the Tokyo Metro, killing twelve people, severely injuring fifty and causing temporary vision problems for nearly a thousand others. The attack was directed against trains passing through Kasumigaseki and Nagatachō, home to the Japanese government. This was (and remains, as of 2007) the most serious attack to occur in Japan since the end of the Second World War.



Aum Shinrikyo (オウム真理教, literally, "Aum the True Teaching") is the former name of a controversial group now known as Aleph.

The name Aum Shinrikyo derives from the Hindu syllable "aum" (pronounced "omu") meaning "universe" and the Japanese words "shinri" ("truth") and "kyō" ("teaching," "doctrine").

In 2000, after the attack, the organization changed its name to Aleph (א), which is the first letter of the Hebrew alphabet. Their logo has also changed. Despite this, the group is still commonly referred to as Aum.

The Japanese police initially reported that the attack was the cult's way of hastening an apocalypse. The prosecution said that it was an attempt to bring down the government and install Shoko Asahara, the group's founder, as the "emperor" of Japan. The most recent theory proposes that the attack was an attempt to divert attention from Aum when the group obtained some information indicating that police searches were planned (though contrary to this plan, it ended up leading to mass searches and arrests). Asahara's defence team claimed that certain senior members of the group independently planned the attack, but their motives for this are left unexplained.

Before the subway attack, Aum Shinrikyo began its attacks on June 27th, 1994. With the help of a converted refrigerator truck, members of the cult released a cloud of sarin which floated near the homes of judges who were overseeing a lawsuit concerning a real-estate dispute which was predicted to go against the cult. From this one event, 500 people were injured and 7 people died. [1]

Main perpetrators

Ten men were responsible for carrying out the attacks; five released the sarin, while the other five served as get-away drivers.

The teams were:

  • Ikuo Hayashi (林 郁夫 Hayashi Ikuo?) and Tomomitsu Niimi (新見 智光 Niimi Tomomitsu?)
  • Kenichi Hirose (広瀬 健一 Hirose Ken'ichi?) and Koichi Kitamura (北村 浩一 Kitamura Kōichi?)
  • Toru Toyoda (豊田 亨 Toyoda Tōru?) and Katsuya Takahashi (高橋 克也 Takahashi Katsuya?)
  • Masato Yokoyama (横山 真人 Yokoyama Masato?) and Kiyotaka Tonozaki (外崎 清隆 Tonozaki Kiyotaka?)
  • Yasuo Hayashi (林 泰男 Hayashi Yasuo?, no relation to Ikuo Hayashi) and Shigeo Sumimoto (杉本 繁郎 Sugimoto Shigeo?)

Ikuo Hayashi

Prior to joining Aum, Hayashi was a senior medical doctor with "an active 'front-line' track record" at the Japanese Ministry of Science and Technology. Himself the son of a doctor, Hayashi graduated from Keio University, one of Tokyo's top schools. He was a heart and artery specialist at Keio Hospital, which he left to become head of Circulatory Medicine at the National Sanatorium Hospital in Tokai, Ibaraki (north of Tokyo). In 1990, he resigned his job and left his family to join Aum in the monastic order Sangha, where he became one of Asahara's favourites and was appointed the group's Minister of Healing, as which he was responsible for administering a variety of "treatments" to Aum members, including sodium pentothal and electric shocks to those whose loyalty was suspect. These treatments resulted in several deaths. Hayashi was later sentenced to life imprisonment.

Tomomitsu Niimi, who was his get-away driver, received the death sentence.

Kenichi Hirose

Hirose was thirty years old at the time of the attacks. Holder of a postgraduate degree in Physics from prestigious Waseda University, Hirose became an important member of the group's Chemical Brigade in their Ministry of Science and Technology. Hirose was also involved in the group's Automatic Light Weapon Development scheme.

Hirose teamed up with Koichi Kitamura, who was his get-away driver. After releasing the sarin, Hirose himself showed symptoms of sarin poisoning. He was able to inject himself with the antidote (atropine sulphate) and was rushed to the Aum-affiliated Shinrikyo Hospital in Nakano for treatment. However, medical personnel at the given hospital had not been given prior notice of the attack and were consequently clueless regarding what treatment Hirose needed. When Kitamura faced the fact that he had driven Hirose to the hospital in vain, he instead drove to Aum's headquarter in Shibuya where Ikuo Hayashi gave Hirose first aid.

Hirose's appeal of his death sentence was rejected by the Tokyo High Court on Wednesday, July 28, 2003.

Toru Toyoda

Toyoda was twenty-seven at the time of the attack. He studied applied physics at Tokyo University's Science Department and graduated with honours. He also holds a master's degree, and was about to begin doctoral studies when he joined Aum, where he belonged to the Chemical Brigade in their Ministry of Science and Technology.

Toyoda was sentenced to death. The appeal of his death sentence was rejected by the Tokyo High Court on Wednesday, July 28, 2003, and he remains on death row.

Katsuya Takahashi was his get-away driver.

Masato Yokoyama

Yokoyama was thirty-one at the time of the attack. He was a graduate in applied physics from Tokai University's Engineering Department. He worked for an electronics firm for three years after graduation before leaving to join Aum, where he became Undersecretary at the group's Ministry of Science and Technology. He was also involved in their Automatic Light Weapons Manufacturing scheme. Yokoyama was sentenced to death in 1999.

Kiyotaka Tonozaki, a high school graduate who joined the group in 1987, was a member of the group's Ministry of Construction, and served as Yokoyama's getaway driver. Tonozaki was sentenced to life in prison.

Yasuo Hayashi

Yasuo Hayashi was thirty-seven years old at the time of the attacks, and was the oldest person at the group's Ministry of Science and Technology. He studied artificial intelligence at Kogakuin University; after graduation he travelled to India where he studied yoga. He then became an Aum member, taking vows in 1988 and rising to the number three position in the group's Ministry of Science and Technology.

Asahara had at one time suspected Hayashi of being a spy. The extra packet of sarin he carried was part of "ritual character test" set up by Asahara to prove his allegiance, according to the prosecution.

Hayashi went on the run after the attacks; he was arrested twenty-one months later, one thousand miles from Tokyo on Ishigaki Island. He was later sentenced to death and has appealed.

Shigeo Sugimoto was his get-away driver. His lawyers argued that he played only a minor role in the attack, but the argument was rejected, and he has been sentenced to death.

The attack

The attack, on Monday 20 March, 1995, came at the peak of the morning rush hour on one of the world's busiest commuter transport systems.

  The liquid sarin was contained in plastic bags which each team then wrapped in newspapers. Each perpetrator carried two packets of sarin totalling approximately one litre of sarin, except Yasuo Hayashi, who carried three bags. A single drop of sarin the size of the head of a pin can kill an adult.

Carrying their packets of sarin and umbrellas with sharpened tips, the perpetrators boarded their appointed trains; at prearranged stations, each perpetrator dropped his package and punctured it several times with the sharpened tip of his umbrella before escaping to his accomplice's waiting get-away car.

Chiyoda line

  The Chiyoda line runs from Kita-Senju in northeast Tokyo to Yoyogi-uehara in the west.

The team of Ikuo Hayashi and Tomomitsu Niimi were assigned to drop sarin packets on the Chiyoda Line. Niimi was the get-away driver.

Hayashi, wearing a surgical mask of the type commonly worn by Japanese people during cold and flu season, boarded the southwest bound 07:48 Chiyoda line train number A725K on the first car, and punctured his bag of sarin at Shin-Ochanomizu Station in the central business district in Chiyoda before making his escape.

Two people were killed in this attack.

Marunouchi line


Two men, Kenichi Hirose and Koichi Kitamura, were assigned to release sarin on the westbound Marunouchi line destined for Ogikubo Station.

Hirose boarded the third car of Train A777, and released his sarin at Ochanomizu Station in Chiyoda.  

Despite two passengers being removed from the train at Nakano Sakaue Station in Nakano, the train continued on to its destination, car three still soaked with liquid sarin. At Ogikubo, new passengers boarded the now eastbound train, and they too were affected by sarin, until the train was finally taken out of service at Shin-Kōenji Station in Suginami.

This attack resulted in one death.


Two members were assigned to release sarin on the Ikebukuro-bound Marunouchi line, Masato Yokoyama and Kiyotaka Tonozaki. Tonozaki was the get-away driver.

Yokoyama boarded the 07:39 B801 train at Shinjuku on the fifth car. He released his sarin at Yotsuya.

Yokoyama succeeded in puncturing one of his packets, and only made one hole, resulting in the sarin being released relatively slowly. The train reached its destination at 08:30, and returned to Ikebukuro as the B901. At Ikebukuro the train was evacuated and searched, but the searchers failed to discover the sarin packets, and the train departed Ikebukuro at 08:32 as the Shinjuku-bound A801. As the train was returning to the city center passengers asked staff to remove the foul smelling objects from the train. At Hongō-sanchōme, staff removed the sarin packets and mopped the floor, but the train continued to Shinjuku, and then returned again to Ikebukuro as the B901. The train was finally put out of service at Kokkai-gijidō-mae Station in Chiyoda at 09:27, one hour and forty minutes after the sarin was released.

This attack resulted in no fatalities.

Hibiya line

Departing Naka-Meguro

The team of Toru Toyoda and Katsuya Takahashi were assigned to release sarin on the northeast bound Hibiya line. Takahashi was the get-away driver.

  Toyoda boarded the first car of the 07:59 B711T train bound for Tōbu Dōbutsu Kōen and punctured his sarin packet at Ebisu. Three stops later passengers had begun to panic, and several were removed from the train at Kamiyacho and taken to hospital. Still, the train continued to Kasumigaseki, though the first car was empty. The train was evacuated and taken out of service at Kasumigaseki.

One person died in this attack.


Yasuo Hayashi and Shigeo Sugimoto were assigned to the southwestbound Hibiya line departing Kita-Senju for Naka-Meguro.

Hayashi received, at his own insistence in an apparent bid to allay suspicions and prove his loyalty to the group, three packets of sarin while everyone else was given two. He boarded the third car of the 07:43 A720S train from Kita-Senju at Ueno Station. He released his sarin two stops later, at Akihabara, making the most punctures of any of the perpetrators.

Passengers began to be affected immediately. At the next station, Kodenmachō, a passenger kicked the packet onto the platform; four people waiting at that station died as a result. A puddle of sarin, however, remained on the train floor as the train continued its route. At 08:10, a passenger pressed the emergency stop button, but as the train was in a tunnel at the time, it proceeded to Tsukiji Station. When the doors opened at Tsukiji, several passengers collapsed onto the platform, and the train was immediately taken out of service.

This train made five stops after the gas was released; along the way, eight people died.


On the day of the attack ambulances transported 688 patients, and nearly five thousand people reached hospitals by other means. Hospitals saw 5,510 patients, seventeen of whom were deemed critical, thirty-seven severe, and 984 moderately ill with vision problems. Most of those reporting to hospitals were the "worried well," who had to be distinguished from those that were ill. [1]

By mid-afternoon, the mildly affected victims had recovered from vision problems and were released from hospital. Most of the remaining patients were well enough to go home the following day, and within a week only a few critical patients remained in hospital. The death toll on the day of the attack was eight, and it eventually rose to twelve. [2]

The injured

Witnesses have said that subway entrances resembled battlefields. In many cases, the injured simply lay on the ground, many unable to breathe. Several of those affected by sarin went to work in spite of their symptoms, most of them not realizing that they had been exposed to sarin gas. Most of the victims sought medical treatment as the symptoms worsened and as they learned of the actual circumstances of the attacks via news broadcasts.

Several of those affected were exposed to sarin only by helping those who had been directly exposed. Among these were passengers on other trains, subway workers and health care workers.

Recent surveys of the victims (in 1998 and 2001) show that many are still suffering from post-traumatic stress disorder. In one survey, twenty percent of 837 respondents complained that they feel insecure whenever riding a train, while ten percent answered that they try to avoid any gas-attack related news. Over sixty percent reported chronic eyestrain and said their vision has worsened.1

Emergency services

Emergency services including police, fire and ambulance services were criticised for their handling of the attack and the injured, as were the media (some of whom, though present at subway entrances and filming the injured, hesitated when asked to transport victims to the hospital) and the Subway Authority, which failed to halt several of the trains despite reports of passenger injury. Health services including hospitals and health staff were also criticised: one hospital refused to admit a victim for almost an hour, and many hospitals turned victims away.

Sarin poisoning was not well-known at the time, and many hospitals only received information on diagnosis and treatment because a professor at Shinshu University's school of medicine happened to see reports on television. Dr. Nobuo Yanagisawa had had experience with treating sarin poisoning after the Matsumoto incident; he recognized the symptoms, had information on diagnosis and treatment collected, and led a team who sent the information to hospitals throughout Tokyo via fax.

Defended by new religions scholars

In May 1995, after the sarin gas attack on the Tokyo subway, American scholars James R. Lewis and J. Gordon Melton flew to Japan to hold a pair of press conferences in which they announced that the chief suspect in the murders, religious group Aum Shinrikyo, couldn't have produced the sarin that the attacks had been committed with. They had determined this, Lewis said, from photos and documents provided by the group.[2]

However, the Japanese police had already discovered at Aum's main compound back in March a sophisticated chemical weapons laboratory that was capable of producing thousands of kilograms a year of the poison.[1] Later investigation showed that Aum not only created the sarin used in the subway attacks, but had committed previous chemical and biological weapons attacks, including a previous attack with sarin that had killed seven and injured 144.[3]

During the Aum Shinrikyo incident Lewis and Gordon's bills for travel, lodging and accommodations were paid for by Aum, according to The Washington Post. [4] Lewis openly disclosed that "Aum [...] arranged to provide all expenses [for the trip] ahead of time", but claimed that this was "so that financial considerations would not be attached to our final report".[5]

Aum/Aleph today

The sarin gas attack was the most serious terrorist attack in Japan's modern history. It caused massive disruption and widespread fear in a society that had previously been perceived as virtually free of crime.

Shortly after the attack, Aum lost its status as a religious organization, and many of its assets were seized. However, the Diet (Japanese parliament) rejected a request from government officials to outlaw the group. The Public Security Committee, an organization similar to America's CIA, received increased funding to monitor the group. In 1999, the Diet gave the Committee broad powers to monitor and curtail the activities of groups that have been involved in "indiscriminate mass murder" and whose leaders are "holding strong sway over their members", a bill custom-tailored to Aum Shinrikyo.

About twenty of Aum's members, including its founder Asahara, are either standing trial or have already been convicted for crimes related to the attack. As of July 2004, eight Aum members have received death sentences for their roles in the attack.

Asahara was sentenced to death by hanging on February 27, 2004, but lawyers immediately appealed the ruling. The Tokyo High Court postponed their decision on the appeal until results were obtained from a court-ordered psychiatric evaluation, which was issued to determine whether or not Asahara was fit to stand trial. In February of 2006, the court ruled that Asahara was indeed fit to stand trial, and on March 27, rejected the appeal against his death sentence. Japan's Supreme Court upheld this decision on September 15, 2006. (Japan does not announce dates of executions, which are by hanging, in advance of them being carried out.)

The group reportedly still has about 2,100 members, and continues to recruit new members under the new name "Aleph". Though the group has renounced its violent past, it still continues to follow Asahara's spiritual teachings. Members operate several businesses, though boycotts of known Aleph-related businesses, in addition to searches, confiscations of possible evidence and picketing by protest groups, have resulted in closures.

Aum/Aleph remains on the US State Department's list of terrorist groups, but has not been linked to any further terrorist acts, or any terrorist acts in the US. Aleph has announced a change of its policies, apologized to victims of the subway attack, and established a special compensation fund. Aum members convicted in relation to the attack or other crimes are not permitted to join the new organization, and are referred to as "ex-members" by the group.



  • "Survey: Subway sarin attack haunts more survivors" in Mainichi Online June 18, 2001.
  • Detailed information on each subway line, including names of perpetrators, times of attack, train numbers and numbers of casualties, as well as biographical details on the perpetrators, were taken from Underground: The Tokyo Gas Attack and the Japanese Psyche by Haruki Murakami.
  • Ataxia: The Chemical and Biological Terrorism Threat and the US Response, Chapter 3 - Rethinking the Lessons of Tokyo, Henry L. Stimson Centre Report No. 35, October 2000
  • Tu A. T. (2000). "Overview of sarin terrorist attacks in Japan". ACS Symposium Series 745: 304-317.
  • Ogawa Y, Yamamura Y, Ando A, et al. (2000). "An attack with sarin nerve gas on the Tokyo subway system and its effects on victims". ACS Symposium Series 745: 333-355.

See also

  • Sarin
  • Aum Shinrikyo
  • Underground (stories)
  • Banjawarn station
  • 7 July 2005 London bombings
  • 2004 Madrid train bombings
  • 1995 Islamist terror bombings in France
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sarin_gas_attack_on_the_Tokyo_subway". A list of authors is available in Wikipedia.
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