was a Japanese radical anti-communist and ultranationalist youth who assassinated Inejirō Asanuma, chairman of the Japan Socialist Party, on 12 October 1960.
Yamaguchi rushed the stage and stabbed Asanuma with a wakizashi-like short sword while Asanuma was participating in a televised election debate at Hibiya Public Hall in Tokyo. Yamaguchi, who was 17 years of age at the time, had been a member of Bin Akao's far-right Greater Japan Patriotic Party, but had resigned earlier that year, just prior to the assassination. After being arrested and interrogated, Yamaguchi committed suicide while in a detention facility.
Yamaguchi became a hero and a martyr to Japanese far-right groups, who as of 2022, have continued to hold commemorations to this day. Yamaguchi's actions inspired a number of copycat crimes, including the Shimanaka incident in 1961, and inspired Nobel Prize-winning novelist Kenzaburō Ōe's novellas Seventeen and Death of a Political Youth. A photograph of the assassination taken by Japanese photojournalist Yasushi Nagao won World Press Photo of the Year for 1960 and the 1961 Pulitzer Prize.
Early life
Yamaguchi was born on 22 February 1943 in Yanaka, Taitō, Tokyo. He was the second son of Shinpei Yamaguchi, who by 1960 would become a high-ranking officer in the Japan Ground Self-Defense Force, and was the maternal grandson of the famous writer Namiroku Murakami, well known for his violent novels glorifying the chivalric code of Japanese organized crime syndicates known as the yakuza.
Yamaguchi began reading newspapers starting in his early childhood. Angered by what he read, he became interested in nationalist movements and vehemently critical of politicians. Due to his father's job changes and transfers, Yamaguchi had to move frequently during his childhood, transferring between two elementary schools, three middle schools, and two high schools. As a result, he grew up with few close friends. He lived in Sapporo, Hokkaido for much of his childhood because of his father's work. In 1958, he was accepted into Tamagawa High School in Tokyo, however his father transferred him to Sapporo Kōsei, a local Catholic school in Sapporo. Yamaguchi then decided to move to Tokyo to live with his brother, and transferred back to Tamagawa High School.
Yamaguchi exhibited intense xenophobia from childhood, harboring deep revulsion toward foreigners, particularly Koreans and Chinese whom he perceived as "domineering" over Japan, fueling his early nationalist resentments. He also developed profound hatred for left-wing groups, including communists, socialists, and labor unions (such as Nikkyoso), associating them with post-war incidents like the Mitaka, Shimoyama, Shiratori, and Matsukawa cases, which he viewed as existential threats to Japan's national integrity.
Described as contrarian and rebellious from a young age, often arguing the opposite of others (for example: insisting "left" if someone said "right"), Yamaguchi frequently clashed with teachers over ideological differences and felt alienated in school environments, contributing to frequent school transfers and general isolation. He was portrayed as a lonely youth who ignored parental and school advice, ultimately dropping out of high school to dedicate himself fully to extremist activities. Through the influence of his brother, he began attending speeches and participating in protests and counter-protests organized by various right-wing groups.
On 10 May 1959, at age 16, he heard a speech by right-wing ultranationalist Bin Akao declaring that Japan was on the verge of a revolution, and that the youth must begin resisting the actions of left-wing groups. This speech had a profound impact on him. After the speech, while Akao was planning to go to the next location, Yamaguchi told Akao that he wanted to go along with him, but Akao gently declined. Following this, he formally joined Akao's Greater Japan Patriotic Party.
1960 Anpo protests
Akao was virulently anti-communist and strongly pro-United States. Thus when left-wing protesters, led by Asanuma and the Japan Socialist Party, staged the massive Anpo protests against the 1960 revision of the U.S.-Japan Security Treaty (known as "Anpo" in Japanese), Akao became convinced that Japan was on the verge of a communist revolution and mobilized his followers to stage counter-protests. Yamaguchi participated in these counter-protest activities, and was arrested and released 10 times over the course of 1959 and 1960, within his first six months since joining Akao's party.
Yamaguchi's involvement with the Greater Japan Patriotic Party involved aggressive anti-communist actions, including disrupting left-wing events with propaganda, which led to repeated arrests (at least 10–17 documented incidents in 1959–1960) for offenses such as assault (throwing glue at opponents, striking individuals), obstruction of public duties, property damage, violence, and power abuse.
Examples include driving propaganda vehicles into venues (causing injuries), physical clashes with leftists and police during Anpo protests, and repeated violations despite parental and party leader warnings to curb aggression.
Due to this chronic pattern of violence, he was placed under four years of protective observation, indicating a disregard for legal consequences.
Over the course of his participation in the Anpo protests, Yamaguchi became further disillusioned with Akao's leadership, which he felt was not radical enough. In his testimony to the police after the assassination of Asanuma, Yamaguchi stated that Akao was always talking about taking out left-wing leaders, but was only interested in protests and media coverage, and that Akao would stop him if he ever tried to act on his words. Later in the interview, he stated that he had resigned from Akao's party in order to "lay [his] hands on a weapon" and be free to take more "decisive action".
Akao, who had known Asanuma since their time on Miyake-jima, described him as “a good person, which makes it regrettable to deal with him” (善人だから始末に悪い), a comment some sources suggest influenced Yamaguchi’s motives alongside Asanuma’s statement labeling American imperialism as the common enemy of Japan and China, as recorded in Yamaguchi’s Memorial of Severing the Traitor. Despite this recognition of Asanuma’s personal character, Akao later celebrated Yamaguchi’s act.
Alongside Akao's influence, Yamaguchi was also inspired by the doctrine of the religious movement Seichō no Ie, particularly through founder Masaharu Taniguchi's writings such as Tennō Zettai-ron to Sono Eikyō (Absolute Theory of the Emperor and Its Influence), which Yamaguchi credited in his interrogation records with helping him overcome personal hesitation and embrace selfless loyalty to commit the act,Yamaguchi Otoya, Interrogation Record (Showa 35 / November 2, 1960). Yamaguchi explicitly states reading Taniguchi's work led to the realization that "true loyalty" requires selflessness, resolving his doubts before the assassination.Ishikawa Tomoya, "三島由紀夫と並び称される右翼・山口二矢、没60年とテロの美化," Ronza (Asahi Shimbun archive), November 28, 2020. https://webronza.asahi.com/politics/articles/2020112700005.html. Notes Yamaguchi was influenced by Taniguchi's teachings on imperial loyalty and selflessness before the act. Asanuma himself supported the founder of this movement, Masaharu Taniguchi.Mainichi Shimbunsha, "牧太郎の青い空白い雲/886," Sunday Mainichi, December 11, 2022. https://mainichibooks.com/sundaymainichi/column/2022/12/11/post-1024.html. Explicitly states: "浅沼さんは昭和天皇を敬愛しており、山口少年の宗教団体「生長の家」の総裁・谷口雅春さんの支持者だった。" (Asanuma respected the Showa Emperor and was a supporter of Taniguchi Masaharu, president of Seichō no Ie.) Taniguchi affirmed that Seichō no Ie was neither opposed to the Socialist Party nor aligned with the Liberal Democratic Party.This non-partisan stance is documented in historical accounts tied to Taniguchi's own statements and Seichō no Ie contexts (e.g., emphasizing neutrality across parties while noting practitioners like Hatoyama Ichirō from the conservative side and Asanuma from the socialist side, without organizational alignment to either).
On 17 June 1960, when a right-wing youth attacked Jōtarō Kawakami, a Christian socialist and an adviser to the Japan Socialist Party, he commented:
On 1 July, together with his comrades, he took part in the establishment of the Tokyo Branch of the All-Asia Anti-Communist League.
On 4 October, while searching for an accordion at his home, he accidentally came across a wakizashi (a traditional Japanese short sword). It had no handguard (tsuba) and was kept in a plain white wooden scabbard. Upon finding it, he said: "I decided that I would use this wakizashi to kill."
After paying his respects at Meiji Jingū, he immediately telephoned Takeshi Kobayashi, chairman of the Japan Teachers' Union (Nikkyōso), and Sanzō Nosaka, chairman of the Japanese Communist Party. He planned to request meetings by telling them, "I'm a university student committee member, and there's something I'd like you to teach me." However, Kobayashi had moved to a new residence, and Nosaka was away on a trip, so he was unable to put his plan into action against either of them, and the attempt failed.
Assassination of Inejirō Asanuma
On 12 October 1960, Yamaguchi was in the large crowd of 2,500 spectators at a televised election debate held in Hibiya Public Hall in Hibiya Park in central Tokyo, featuring Suehiro Nishio of the Democratic Socialist Party, Inejirō Asanuma of the Japan Socialist Party, and Hayato Ikeda of the Liberal Democratic Party. Asanuma was the second to speak, and took the stage at 3:00 p.m.
At 3:05 p.m., Yamaguchi rushed onto the stage and made a deep thrust into Asanuma's left flank with the 33-centimeter replica "wakizashi" he had stolen from his father. He was then swarmed and detained by bystanders. Bin Akao, who was present at the debate, reportedly remarked to someone nearby upon noticing the limited bleeding, "Little boy (Yamaguchi), did you miss your chance?" (坊や、やりそこなったかな). Asanuma was then rushed to a nearby hospital, but died within minutes from massive internal bleeding.
At the time of his arrest at the scene of the murder, Yamaguchi had a notebook in his pocket describing Asanuma's actions as unforgivable, as well as detailing his motivations for the attack.
In this note, he made mention of political controversy surrounding Asanuma's support for the then recently proclaimed People's Republic of China, the June 15th Incident during the Anpo Protests, as well as concerns over Japan potentially becoming communist.
In the days following the assassination, an imperial envoy visited Asanuma's home in Shirakawa Town, Kōtō Ward, to deliver a sacrificial offering (saishiryō) from Emperor Hirohito, Hirohito publicly appealed for public order and obedience to the law. In a speech opening a special session of the National Diet on 18 October 1960, the emperor urged the Japanese people to "esteem the principle of obeying the laws" and to "shun violence", remarks widely understood as alluding to the killing of Asanuma and the unrest that followed. Contemporary observers described the address as the emperor's closest approach to intervening in a matter of grave national political concern since his renunciation of divinity in 1946.
The loss of Asanuma's adroit leadership and the new leadership that followed caused the party to head in a more centrist direction, and deprived the JSP of its ability to present a cohesive message, leading to severe infighting within the party. As a result, the number of seats the socialists held in the Diet continued to decline until the party's extinction in 1996.
Yamaguchi's perception of Asanuma