Ishii graduated from Chuo University, where he studied the legal educations and the graduate school of Waseda University. During the student time, he has participated in Student activism. Ishii lived in the Soviet Union for 6 years as an international student to Lomonosov Moscow State University, following the recommendation by Yasushi Akutagawa, Representative of Japan-Soviet Union Youth Friendship Committee at that time. There he majored theory of state and law under the guidance of Professor A. Y. Denisov and earned a doctorate in philosophy.
In 1999, Ishii formed a bipartisan group in the Diet to track Aum Shinrikyo members. He played an active role in exposing the activities of Aum Shinrikyo in Russia, where it had continued to operate. In 2000 Ishii opposed the screening of Battle Royale considering its contents that students kill each other until only one is left, and asked Tadamori Oshima, the Minister of Education at that time for the government opinion towards the film in the 150th Diet. Ironically this attracted the public interest so that the film grossed ¥3.11 billion domestically.
Final year in the Diet
In 2002, Ishii intensified his investigations into the Japanese budget and proposed that the real government spending of the Japanese Government is about 200 trillion yen, much of which was being concealed from the public. Masajuro Shiokawa, the Finance Minister at that time, refused to comment, claiming that Ishii was merely expressing an opinion. Spurned by the legislative process, Ishii wrote a book about his discoveries, Japan's Secret Checkbook: The Truth about the Financial Interests That Will Destroy the Nation. It was published by a small alternative press.
Murder
On 25 October 2002, Ishii was stabbed to death by Ito Hakusui, a Yamaguchi-gumi gangster. Ishii was the third Japanese politician murdered after the end of World War II. Ito escaped down the road covered in blood in broad daylight and fled to the mountains without being noticed, but surrendered himself the next day. Ito said he killed Ishii because Ishii refused to pay a bribe. The police claimed that Ito had "personal" motives, making a larger investigation unnecessary. On 15 November 2005, the Supreme Court sentenced Ito to life in prison without being able to determine a motive. After Ishii's death, a by-election was held in Tokyo 6th District on 27 April 2003, and Yoko Komiyama of DPJ was elected to the House of Representatives. Ishii's family refused to endorse her.
Noriyuki Imanishi, an investigative journalist, claims that Ishii told him just before his death that he had "discovered something terrible." His wife and staffers reported that Ishii made similar statements to them. Ishii had been about to make an address to the Diet when he was murdered, and that day he was going to the Diet to deposit confidential papers. In the chaos after the murder, his briefcase was emptied by an unknown person. Imanishi and others close to Ishii suspect assassination. In 2008, Ito renounced his sworn testimony that there were "personal" motives for the assassination, and now claims that he had been hired to kill Ishii. In October 2010, Asahi TV aired a primetime special on the murder, and an expert claimed that forensic evidence showed Ito was attempting to seize Ishii's briefcase. Asahi interviewed Ito, and received the following replies: According to Diet member Nobuto Hosaka, there were a number of suspicious circumstances surrounding the murder. Hosaka wrote on his blog that the police squad in charge of the murder did not do even simple things like swabbing for fingerprints, and that Ishii's diary also went missing at some point after his murder. For Hosaka, the single most disturbing thing is that reporters had called him asking about Ito immediately after the murder, a full day before any suspects had been announced. The Asahi TV documentary did not report this incident. Since 2004, Ishii's family has offered a reward of 1 million yen for any information about the murder.
