Yamaguchi was a left-wing organizer and at the May Day rally in 1920, some of his union members had shouted anti-colonial slogans; Japanese police responded with arrests and abuse.

On September 1, 1923, immediately after the earthquake, Yamaguchi organized his union to provide food and water to the neighborhood, including commandeering supplies from ruined buildings.

"[11] According to multiple reports from Japanese witnesses, beginning on the night of September 2 police officers in Yokohama, Kanagawa and Tokyo began informing residents that it was permissible to kill Koreans.

[16][17] As a result of the police-initiated rumors, beginning on September 2, Japanese citizens organized themselves into vigilante bands and accosted strangers on the street.

The ethnic Japanese playwright Koreya Senda was targeted by a mob, and wrote of his experience in 1988: On the second night after the earthquake, there were foolish rumors about Koreans who were allegedly on their way to raid the town to get revenge on the Japanese [...] It turned out that I was mistaken for Korean, and they wouldn’t believe me even though I denied it over and over saying, "I am Japanese…I am a student at Waseda University," with my student ID at hand.

On the morning of September 3, the Home Ministry of Mizuno Rentarō issued a message to police stations around the capital encouraging the spread of rumors and violence, stating that “there are a group of people who want to take advantage of disasters.

[24] Official Japanese reports in September claimed that only five Koreans had been killed, and even years after, the number of acknowledged deaths remained in the low hundreds.

Based on their testimonies, Japanese eyewitness accounts, and additional academic research, current estimates of the death toll range from 6,000 to 9,000.

[24] Amidst the mob violence, regional police and the army used the pretext of civil unrest to liquidate political dissidents.

[28] Socialists such as Hirasawa Keishichi [ja] (平澤計七) and the Chinese communal leader Wang Xitian (王希天), were abducted and killed by local police and army, who claimed the radicals intended to use the crisis as an opportunity to overthrow the Japanese government.

The incident caused national outrage, albeit thousands signed petitions requesting leniency on Amakasu's behalf.

During the trial, Amakasu's lawyers tied the murder to soldierly duties, and the ideals of spontaneity, sincerity, and pure motives.

[33][34] On September 5, after Prime Minister Uchida Kōsai acknowledged that unlawful killings had occurred, Tokyo officials met secretly to discuss a way to deny and minimize the massacre.

Tokyo police chief Maruyama Tsurukichi ordered the Sōaikai to confine Koreans to the camps to prevent them from spreading news of the massacre abroad.

After being held in prison for several months he was finally prosecuted only for redistributing food and water from ruined houses to earthquake survivors without permission of the homeowners.

[45] The Governor-General also published and distributed propaganda leaflets with "beautiful stories" (美談, bidan) of Japanese protecting Koreans from lynch mobs.

[11] After the massacre, Navy Minister Takarabe Takeshi praised the Japanese lynch mobs for their "martial spirit," describing them as a successful result of military conscription.

"[49] In 2000, the Governor of Tokyo Shintaro Ishihara received international criticism for claiming that sangokujin (a term originally referring to foreigners, and now considered xenophobic and harsh) could be "expect[ed] to riot in the event of a disastrous earthquake".

Miyoko Kudō's 2009 book The Great Kanto Earthquake: The Truth About the "Massacre of Koreans" (関東大震災「朝鮮人虐殺」の真実) was influential in inspiring grassroots-level attempts to whitewash the issue in official and public commemorations.

[55] Beginning in 2017, Tokyo Metropolitan governor Yuriko Koike broke decades of precedent by refusing to acknowledge the massacre or offer condolences to the descendants of survivors.

[59][58][60] However, the memorial ceremony is regularly met with counter protests, especially by the organization Japan Women's Group Gentle Breeze (日本女性の会そよ風, or "そよ風").

"[63][64] Ramseyer also drew controversy that same year for describing "comfort women" (a euphemism for forced prostitutes) as engaging in a "consensual, contractual process".

The editor of the handbook in which it was published, Alon Harel, said of the paper's disputed portions: "It was evidently an innocent and very regrettable mistake on our part.

In the meantime, we have learnt a lot about the events and we sent a list of detailed comments on the paper that were written by professional historians and lawyers".

A reporter for the Mainichi Shimbun claimed that this contradicted a previous personal statement from Matsuno in 2011, when he acknowledged that killings had happened during the massacre.

In 2014, he published September: Echoes of the 1923 Great Kanto Earthquake Genocide on the Streets of Tokyo (九月、東京の路上で 1923年関東大震災ジェノサイドの残響, Kugatsu, Tōkyō no rojō de 1923-nen Kantōdaishinsai jenosaido no zankyō).

[77] Prewar narratives by Koreans frequently appealed to a Japanese readership to heal the wounds which were caused by ethnic divides, while in the immediate postwar period the "emperor system" was blamed for brainwashing massacre participants to act against their better instincts.

Ri Kaisei's 1975 novel Exile and Freedom exemplifies this turning point with a central monologue: "Can you guarantee that it won't happen again right here and now?